I don't believe you.
Thief class could have been a bad decision, but that boss had some pretty cheap one hit deaths. Booshka's post pretty much explains it all, the controls are almost purposely shit.
Nah, controls are very good, you just have to learn them. I wasn't used to attacking with the Triggers and Bumpers, but once you get used to it, you understand the game demands that control scheme.
I was pressing X to attack all the time and using items or switching weapons when I pressed Y to use a heavy attack. Got over that soon enough, and learned the controls.
And Thief is a bad class to start, play Pyromancer, Warrior or Bandit. Much stronger starting classes.