To those saying that rogue's are a weak class/don't do enough damage: What the bloody hell are you smoking? As was stated, rogues are easily the highest sustained damage in the game. You're probably just spending your attributes and skills badly.
There are three ways to play a melee rogue: First is full strength with some dex, or the Rogue-Who-Thinks-He's-A-Warrior. Good damage, good survivability thanks to beefy armors, boring to play. Next is full dexterity, or Ghost Rogue. With full dex, you will always hit your enemies and never be hit by them. Fantastic survivability, decent damage. Fun to play 'cause you're a soloing fiend.
And then there's my favorite: full cunning with some dex, or WTFBACKSTABLOLBBQ!?!? Rogue. With a pair of good daggers and a boatload of cunning to take advantage of lethality, your rogue will become a backstabbing machine of death. If you combine further with rogue abilities like momentum (backstabs every .5 seconds), coup-de-grace (insta-backstab on anything stunned/paralyzed), good poisons, and proper party buffs like Telekinetic Weapons and the Champion's aura, then I cannot begin to emphasize the sheer killing power you will emit. We're talking 100 damage backstabs every half second. Seriously; Shit. Will. Die. This build does merely decent damage when not backstabbing, has survivability based solely on killing other dude before he can hurt you, and requires complete micro-management, but is still incredibly fun to play. Also has the benefit of being able to open anything in game without a single point in deft hands.