Hey! since I've been mostly focusing on pvp lately I figured I would say some of the pvp issues I think are coming up for illusionist lately 
Illusionist Sentinel's Fate Issues: PVP Related
DPS
Ok so its pretty common knowledge now that Illy pve dps is pretty bad. From estimates I've heard we peg that somewhere near Warden and Inquisitor dps when they care enough to dps. But there are drastic changes between pvp and pve mechanics that change where classes stand that need to be taken into account. Unfortunately, for avg illy dps in bgs this means its even WORSE. I've seen avg illy dps get to about the lvl of Defiler when they spec for offense due to several factors:
-We have to trade off a large portion of offensive gear and red adorns for toughness and pvp crit mit in order to be able to gain enough survivability in order to compete (and moreso than other classes).
-Furthermore illys will sometimes trade gear for other factors such as gaining mutilation procs, or strength in order to avoid or lessen the ridiculous 1+ minute long strength debuffs causing burdening that several classes have currently that have no immunities and are easily reappliable.
-We have no dmg aoes and only two group target dmg spells making our non single target dps much lower than other classes. Oh yea we have a self buff that gives our weapon a chance of aoe autoattack, which seems good until you consider- 1) Our weapons do crap dmg, and 2) In order to use it we have to get into melee range where we will be beaten to a pulp by any melee class because we have one of the worst class survivabilities. In pvp group dmg mechanics end up determining dps much more.
-Our hardest hitting spell, prismatic chaos, loses much of its viability: 1) depending on your gear setup the red adorn is lost and thus the two additional hits, 2) If we self cast it the rate at which we hit is slow and takes way too long for us to benefit from it, 3) It puts us into the opponent's melee pummeling range for an extended period of time while we have it fire off, 4) its melee range also means that we have to close in 15m ish before we can use it solo, which destroys our ability to kite and hurts its dps even more because we could be casting other spells in the time it takes to close in that gap (it essentially acts like an addon to cast time if you close in for the purpose of using it), 5) its very difficult to incorporate into most bg matches by putting it onto other people, because a) its hard to find people that actually stay in range or with your group to put it on, b) don't attack dumb targets and be worth putting it on, and c) its very hard to target those ppl and get it off in time and consistently due to broken taunt mechanics, and also other cc, interrupts, and detargets.
-PVP has a larger focus on burst dmg than overtime dmg from variuos sources that builds. While illy has a slight burst dmg effect from Time warp, our main spells are low dmg dealing and dot spells and most get mitigated away to almost nonexistant levels. And even if not mitigated out dot still has a natural disadvantage against burst dmg because of healing over time, and health regens that negatively impact the overall effectiveness of longer spell durations. Plus the risk of incoming dmg from longer durations
-DOTS are almost all immediately cured in group settings leaving only really the initial hits worth of dmg.
-Due to our lack of survivability we are unable to take on too many targets at a time without extreme risk of death without healer and tank support. Whereas healers and tanks can jump right into 3+ ppl and start dpsing all of them.
-2h, dual hand and bow dmg increases lately leave spell dmg comparatively behind.
-Illy lacks debuff options other classes like coercer have.
-And finally our dps is achieved mainly by constantly and frantically being attentive to our spell orders and dmg casting. When we need to break for crowd control or dispels or detargets or ports etc.. which play a much more prominent role in bgs, it directly effects our ability to dps, whereas other classes can achieve much higher rates of dps while still maintaining other roles due to their high dmg spells being from fewer and more accessible sources.
Crowd Control
The use of crowd control as a survivability measure for illusionist as well has been negatively impacted in many ways this expansion, a small part of which may have been warranted at the time, but as of now in solo or small group combat is at best useful but not a consistently reliable means of survivability and at worst obsolete. This is obviously a major concern because our crowd control is our core benefit over other classes, and unlike other classes our core moves are now both easily bypassable and we lack almost any other comparative benefits to reconcile any reasonable chance of success once they are bypassed (if they get past we are left with comparatively bottom tier dps and survivability).The reasons for this drop in cc pvp usefulness stem from several factors:
-Post expansion there was a large influx of pvp items offering cc dispels (which if done right is basically an immunity due to the immunity caused by cc) and immunities. As well as there being the already various attainable options and class spells (both individual and groupwide) that limit any usefulness they might bring. Most healers, crusaders, and brawlers for example already had intrinsic advantages over our class from their aa line immunities, but the new items allowed almost any class to have major advantages over enchanter if equipped properly. Zerkers, for example, just love the old tso items that proc 15 second spell immunities on incoming dmg, which, given the dmg they need to take and the fact that since enchanters rely on smaller fast casting spells means we proc it more often than other classes, means the zerker is essentially permanently immune in group settings. Predators, by contrast, only need the freedom of mind pots really because after they dispel the stun or root they can easily kill the illy in the time it grants them, not that they need to dispel the root since they can pretty much autoattack dmg at more range and more dps than illy. Essentially, crowd control options have put most any class that utilizes them properly at a drastic advantage over illy and which has nothing to do with the skill of the players involved.
-The dispel options, immunities, and class traits that prevent cc aren't the only things that block proper use of cc though: wards while they don't directly stop cc destroy our ability to do any dmg to our opponent while they are incapacitated, tanks which are mostly cc immune constantly taunt us off of vulnerable targets, abilities like shadowstep port out of root making it obsolete, defensive classes have high resist rates against some cc, but most of all:
-The recent increases to bg defense including the toughness and pvp crit mit changes in conjunction with our very very low dps and in relation to the around expansion changes to cc including lowering of cc durations and longer immunities, means that even if we do get off cc our ability to capitalize on that disability period is very very small. For each 4-5 second stun for example we really are only able to get off maybe 2 spells before we need to buffer the next control effect (usually stifle imo). And those two spells just aren't going to do much comparatively to other classes, and comparatively to what they usto do since pvp is so defensive heavy now.
-The range of Illusionist cc has a base of around 25m which is very small in comparison to spell range and bow range both of which usually extend on to 35-50m base. This means its really easy for some classes to not even have to approach within cc range of us and win, especially when predators also have stuff like better in combat run speed, higher ranged dps, and stuff like snares and str debuffs that make it very unlikely that we will be able to close in range. Fortunately, 95% of rangers in bgs for some reason don't know how to back up.
-Finally for being a crowd control class illusionist is surprisingly not that good at it. Tank taunts easily have better utility in group settings for keeping dmg off of key targets (i.e. crowd control) because they are spammable, reappliable, have low recasts and no immunities. Scouts also have better crowd control in many ways, snares and debuffs last unnaturally long times and again don't have immunities, are easily reappliable and have less immunity options, and scout stifles/stuns generally have much longer durations and less immunities. Tanks and scouts are both surprisingly well at it considering they also get massive dps and survivability. It seems enchanter cc is one of the most restricted types of cc both in terms of usage and opponent options over all other cc. Of course this is still a definite step up from illy pve crowd control usefulness... but still, I really love being able to work around cc in pvp its one of my favorite aspects so I hope it becomes more balanced in high level play.
Survivability
As its pretty straightforward, I won't spend too much time discussing this, especially when most of it has already been brought up previously. Its not hard to see that enchanter ability to take dmg is one of the worst in the game in comparison to other classes on a similar gear level. This is brought out more than it should be due to the ability to bypass crowd control, but is also a major factor because illusionist has a higher percentage of combat arts, and low and melee range spell dmg in comparison to other classes that force illusionist to have to approach more than usual in order to attack. Another issue with survivability is that in the absence of cc or against multiple targets there really isn't that much we can do defensively, not just in our comparative dmg taking abilities, but our other defensive options basically come down to short range ports and temporary targeting distractions that are both easy to get around. The one good thing about enchanter survivability though is that smaller fast spells allow us to proc healing adorns more, but it still doesn't bring us to the levels we should be at in order to compete.
Pet
Finally I figure our personae reflection deserves its own category:
-It is one of the few pets that are dispellable (and one of the first illy spells that will be too)
-Has near negligible dps
-Can interfere with mezzes
-In open world pvp lags visibly behind you and makes it difficult to stealth/invisible
Not that the its entirely bad its still useful especially to do some range or out of line of sight dmg/cc and in order to attack while you are disabled.
Mana Drains
Specifically the manatap and absorb magic spells almost never ever work, it takes a really really long time to drain any classes mana if they have mana procs or items, and even when the classes' mana is low and you start spamming it chances are they will just get someone to feed them, hit their mana feed/drain/item spell to restore it, or just slow casting or run off for a bit to regain it. Mana drains only really start benefitting you when the player's mana is totally out, and its very hard for that to happen and last.
In conclusion, I think there is a lot of factors right now that are pvp specific that make it difficult for illusionist to fairly compete with other classes in high level play that I hope are balanced out in the future. It would be nice if crowd control for example was balanced out and immunity options were reduced so its usefulness comes down to something other than luck in having dispel items etc... and illy dps was raised to account for decreased usefulness in pvp (except if you are rolling a premade I guess). Illusionist needs some love 