I thought Troy was mediocre. One of those movies where you might want to see it in the theater if you have nothing better to do, but waiting until it comes to DVD wouldn't be a bad choice either.
It's natural to compare it to Gladiator, so I'll say that I liked Gladiator much more than Troy. Maximus was such a great character to build a movie around, while Troy doesn't have any "protagonist" who's nearly as interesting. The closest it has is probably Achilles (Brad Pitt), but......let's just say, he ain't no Maximus! (Though I don't know whether to fault the performance or the script for that shortcoming.)