I haven't had any problems with my warrior in 12v12. In fact, rather than tinker with the new professions, I took my Prophecies warrior and drove her through the arena for most of my time.
What's on her bar?
Savage Slash
Glimmering Blade (I think it's called this, anyway)
Fear Me
Riposte
Deadily Riposte
Gladiator's Stance
Shield Stance
Healing Signet
I didn't bother with a res.. 'cause, well, it's 12v12.
And, with that, I was able to hold my own against every melee build. Against casters, I'm simply there to annoy them--damage them, interrupt them, dent their energy.
Normally, when I do this, melees start coming after me.

Did I feel underpowered? Not at all.
Did I suffer from massive degen from time to time?
Yep.
I didn't see this as some horrible character flaw, though. Rather, it's.. simply part of the game--part of the strategy involved. If you're dealing with massive degen, find a way to deal with it.

In any case..
"Warriors were always underpowered - just try killing any anti-war build or prot monk with war and see.
And assassins = wars with no adrenal skills.
Why? Because they only have enough energy to do 1 combo before they're useless."
Chumsy said that. ;P
I agree on the assassins. Not because I played one (I avoided doing that the entire event), but rather because my guildies noticed that. Said with any amount of DP, an assassin becomes useless quickly 'cause of how much energy it takes to pull a combo.
Glass cannon.

I especially love assassins as a warrior 'cause I can block their attacks, thus ruining the chain. ;P
- edit -
What Ensign said.
Everything has a counter. Every counter has a counter. One simply has to be prepared. I don't really see any class as over/underpowered. Just people don't feel like taking a possible counter or are ignorant of those counters.