I saw it last night and really enjoyed it. Keep in mind that this is a drama and not an action movie. There wasn't a lot of action, but what action there was, was extremely violent and very well done... as is the case in all Michael Mann's movies. In other words, if you're expecting it to be like "Bad Boys", don't bother seeing it.
I give it a good solid B which might go up to a B+ after I watch it again. It was definitely good enough for me to buy on DVD.