I didn't think Troy was that bad.
Agreed, Troy was very well done in parts. At least Brad Pitt surprizingly (to me) showed he could carry a film, even though his character, Achilles, was odd for a modern day audience to identify with.
Alexander, on the other hand, was one of the most horrid bits of bad casting, lack of charisma and poor blonde dying I ever hope to see. A whining gloomy world conqueror!
I didn't think Troy was that bad, either. But then we watched it at home on DVD, with adult beverages in hand. That usually helps.