This guy is beast at mobbing. I have 3 level 60 characters: Gladiator, Enforcer, and Lawbringer. They are all great in their own way, but my level 57 Claptrap is the best I’ve seen at general mob control. Using cryo weapons seems to work very well with him, even though I don’t really have him spec’d for that. Any of the Hail smg’s are awsome with him. I also like using the Zim and Ravager combo for tough mobs.
I haven’t really figured him out yet for taking down bosses. I am able to take them down, but with difficulty. He does however take down Ultimate Badasses very easy.
For my playstyle I have found a good Adaptive shield, Vanquisher mod, and the Eddie OZ kit to be the best for me.
I don’t consider myself good at making builds, but this is what I am currently using: http://thepresequel.com/Claptrap/055115150010550515150000300000000000