Stephen Hunter at the Washington Post writes about Miami Vice: "The worst news about Miami Vice is that Colin Farrell and Jamie Foxx, replacing Don Johnson and Philip Michael Thomas in the key roles, don't hold a candle, a flashlight, a freakin' match to the original guys."
I find this very easy to believe, although I haven't seen the movie (yet). There's an almost cliche quality about TV stars that works quite well in police shows. Modern movie stars have to be subtle actors, humble with the cast and crew, and "real". This sort of role doesn't lend itself to those traditional strengths.