As others have said:
Arsenal - good burst - quick initial damage, but needs to turret to finish the job it seems.
IO - good damage over time, if left alone you can tear some classes apart (but isn't that the case for anyone?).
Overall - we're often destroyed in pvp.
It's been my main since beta, and in pvp I'm often worthless unless the other team simply ignores me (or if we have a healer that'll spend 90% of their time on me), but IF that happens, I can put up some very nice damage and kills. But it almost never happens. We're just too easy to kill.
Assassins, PTs, Sorcs and Juggs pretty much just laugh at me as they kill me.
PTs I can hurt, but I'll lose. Sorcs I can hurt, but I'll lose and they'll be healed up before I can even respawn.
Assassins and guardians - seems I can't do squat to them at all. Especially assassins. If a jugg blows his CDs, sometimes I can leave a mark. Assassins...ya, it's just as effective if I stand there and die instead of attack.
This is what I find, anyways. And yes, I know I'm not the best at pvp. I do the best I can do. And I am persistent.
What is horrible though is when I do venture in to ranked (sometimes I just feel like taking abuse I guess). Ranked often offers 2 forms of humiliation - being insta-killed, and having your team tell you how awful you are for being insta-killed.