Then in the black hat, we have Carrey's character, who is an utterly one-dimensional stupid jerk, and whose comeuppance is entirely his own fault. There's no humanizing of him where there easily could be - Burt's a dick, so it wouldn't be hard to give him an antagonist who's mildly sympathetic and thereby complicate the dynamic a bit. But no, Steve is just dickier.
Now, it could be that I'm being unnecessarily demanding on my magic movies, as I didn't care for The Prestige's sudden detour into sci-fi and cloning either. But setting a movie in this world requires research, not just of the personalities involved but the trick techniques as well. How does Carrey vomit forth endless (non-puke covered) candy as a human pinata, or how would he in the real world? I don't know, and I suspect the writers don't either - they just wanted a gross-out gag.
There are some fun supporting turns here: James Gandolfini as the ultimate absent father, Jay Mohr as a low-rent magic comic who can't ever quite tell a joke properly (and isn't it ironic that he's still funnier than most of the polished humor on display?) and Alan Arkin as the original magician who inspires Burt, particularly funnily in flashbacks under a bad toupee and thick makeup for el cheapo de-aging effect. I don't think the acting is the problem here, but the material. Fool me twice, shame on me; fool me never, and you shouldn't be in the prestidigitation game.