Disappointing. There were two things that kept this from working for me. 1) Director David Ayer makes one fundamental fatal flaw with this movie that ruined it for me. And that is filming it in POV/found footage type and it gets so annoying, particularly during the first half. Consequently, I was never truly able to get into this movie. Maybe it'll play better on television. I'll give the movie another shot when it comes out on Blu-Ray. For now, it just didn't work for me.
The other thing I really didn't like about the movie is that the bad guys are such wildly cartoonish caricatures that they are actually quite annoying.
On the plus side, it's well acted. The chemistry between Gyllenhaal and Pena is definitely the best thing about the movie. The best scenes in the movie, without a doubt, are the scenes between the two of them alone in their police car, talking and patrolling the area. Pena is especially good, delivering the movie's best performance and might even be worthy of an Oscar nomination. There were a few scenes where, not only did the POV stuff not interfere with the movie, but even kind of aided it. This is especially true during the movie's climax. And the ending was definitely moving. And kind of surprising too.
But overall, I found this movie to be pretty disappointing. Definitely Ayer's weakest effort to date as both a writer and director.