I'm using the UA in Adept III version, and to be honest with you guys, it's pretty damned uber. It is a very tough pet, and it hit's pretty hard.
I can pull a mob using the 2 lowest level dots I have, and he will take the aggro right off me. I've even blighted a mob with an adept III blight spell and had him take the aggro away from me. And he can soak up the damage as well as dish it out.
He might not be as flashy looking as the spider pet, but imo he's a hell of alot better when you compare adept III to adept III.
So far, I'm alot happier with this pet than I am with the Spellbinder. I never did like the spellbinder much, simply because I really take advantage of trading pet health for power, and the GS just couldn't take that kind of action.
This pet though I can suck the life out of him like mad, and do it even while he's fighting white cons, and he's unfazed by it.