Although the phrase 'The best Michael Bay movie ever' may not be an actual compliment in a lot of circles, '13 Hours' is a solid 7 out of 10 and better than almost every movie that I saw in 2015. It is the successful modern warfare movie that the highly confusing 'Black Hawk Down' and the very dull 'Zero Dark Thirty' were not.
Showcasing a big cast of likable (and discernible) characters and some good (albeit slightly confusing) action set pieces, this movie bears comparisons to the HBO series 'Band of Brothers' and 'Generation Kill,' which it more strongly resembles, but it is actually a bit better than those good shows, thanks to the very likable, better differentiated ensemble cast of characters and the uncomfortable, but steady ratcheting of the plot. And unlike 'Black Hawk Down' and 'Zero Dark Thirty' almost all of the drama here actually works. The grisly moments are well--and dryly--handled, and the performances are good, and in some cases--such as with Schreiber, Denman, and Krasinski--very good.
None of the flaws are severe. Mostly, they are limited to the (expected) overcutting of the material, the occasional stylistic flourishes that don't quite gel with the rest of the movie (e.g. the mortar shell point of view), some scenes that are explained rather than shown (eg. the guarding the ambassador during his public appearance), and a handful of line readings of the wisecracking dialogue that don't seem as natural as those that are in the rest of the movie.
In terms of morals and messages, '13 Hours' was noticeably grayer than I was expecting it to be, especially considering the director and that it was based on a true story. If I did not know who directed this, my first guess would actually have been Michael Mann--the visuals really have that lose, purposefully ugly 'Collatera'l and 'Miami Vice' (2006) feel--though this is certainly a much more sentimental picture than anything that Mann has made in decades. A surprisingly good ensemble war event along the lines of 'Men in War' (1957) and 'Battleground' (1949). Recommended.