Idk. Tom Cruise is a pretty muscular dude, and a decent actor. As an actress, those things would appeal to Katie Holmes. And she probably just looked past the whole Scientology thing, until he wanted it for their daughter. I've never been AMAZED with Tom Cruise, by the guys got some good movies (Rain Man, Magnolia, Minority Report...) and, while a crazy dude, he deserves some credit.
It was probably one of those fairy tale things.. She did state she always wanted to marry him... You know a rich guy sweeps u off your feet, you have a fairy tale wedding, then you find out he isn't what u thought.