I have a 50 Carnage warrior and a 34 Juggernaut...
On the marauder, 1 on 1 you SHOULD win almost any fight. But when you pop cooldowns, it gets tougher. In warzones I felt largely useless, as when you are melee you attract alot of attention, as opposed to a sniper hiding in the back. You can get destroyed pretty quick, and though you do have undying rage, when thats on cooldown, get ready to die fast.
That said, when I hit 50, I realized that DPS in group combat wasn't my bag. So after a couple flashpoints, I immediately re-rolled as a juggernaut.
Best. Decision. Ever.
Marauder, totally bad ***. So much fun solo in PVE. Juggernaut, as an immortal spec, Throwing guard, force pushing, throw in a couple stuns, much more my style. Taunts all around. Though I've never played a tank spec before, I feel unbelievably more useful in warzones and group situations. I went from 4-5 medals to 6-7 consistently (if thats something you care about).
Of course, this is going from a DPS spec to a tank build. But the tanking in PVP is alot of fun, useful, and even rewarding.