I am a die hard Bruce Willis fan (no pun intended) and it certainly wasn't him or Mos Def that kept this movie from being spectacular. Bruce Willis gave a very good performance, despite the fact that his role closely represented the same character he played in "Sin City." Mos Def performed incredibly well. Certainly his best performance to date.
The performances of both Bruce Willis and Mos Def are probably the only element that kept this movie from completely bombing. Any other cast and it would have been a flop (duh).
"16 Blocks" is a great action movie if that's what your into. The way I like to put it however is it's a good "twist(s) on an already overdone and cliché story line." I would go into further detail but I wouldn't want to spoil it for all of you. With plenty of suspense there isn't a dull moment that I can remember. This movie is definitely worth seeing if you like Bruce Willis or Mos Def. If not, then save your 9 bucks and rent a movie instead. If you are a Bruce Willis fan then maybe its worth it. If you're only a Mos Def fan and don't like the Bruce man then maybe the matinée price would better suit your tastes.
Enjoy.