I've seen some films where I liked Cruise a lot in A Few Good Men. He was okay in Rain Man, but seriously overshadowed by Dustin Hoffman. I haven't seen The Last Samurai, but I think his performance was astounding in Born on the 4th of July.
There's only one actor I detest to the point of refusing to see his movies, and that's Jim Carrey. I started boycotting him after seeing an interview where he kept pulling the same faces he always seems to, judging by the trailers I haven't managed to avoid...
In general, I don't much care about what political or religious opinions actors or other celebrities may have, but I think Cruise did cross the line with his performances on various talk shows, and with his comments about medicating mental disorders.
That said, Cruise has apologized for his comments and sent Brooke Shields a huge bouquet of flowers, when it turned out she was in the same hospital giving birth to her second child while Katie was in labor with her first.
I'm not keen on proselytizing religions in any case, and don't have much respect for Scientology, which was basically invented by a science-fiction author to show the gullibility of some people, on a bet. Too bad he ended up believing in it himself... John Travolta is a Scientologist too, and you don't get him going on about it in public.
One celebrity whose opinions I really despise, though, is Mel Gibson. He's had his brains addled by extremely conservative Catholicism, witness his spouting off anti-Semitic comments at police officers recently when he got arrested for drunk driving. His apologies afterwards have come across as a belated attempt to smooth things over. Being drunk only removes inhibitions to spout off when you would know better while sober, it doesn't make you rave about ideas you really don't believe in.