That would be the point. That, along with the other details of his life slowly being consumed by his less redeeming traits is what makes the play a tragedy, instead of a comedy. It starts with his pride (his overbearing intelligence), and then it begins drawing him to the other seven deadly sins, including a scene between him, Mephistopheles, and the personifications of all of the deadly sins.
It's a pretty interesting play, but there are some rather interesting parts interspersed with incredibly boring parts. You'll either love act IV for its slapstick-esque comedy or find it pointless, because it doesn't ever match the tone of the rest of the book. In any case, this was a work written before epic plot twists.