Ben Affleck is the most solid director of his time (of course, three movies). He's admirably consistent: good casting, good camera work, and good pace. He may be inheriting the Coen Brothers (or a better version of Clint Eastwood) spot of every movie being expected to be solid, award-contending stuff. However, he's not a star. However, you don't expect him to do something brilliant.
What we have here is a pretty wild premise. It's something you would make a B/C-movie of, or a comic book for those publishers I don't like. It's crazy. But it's a true story. I don't really get the appeal of a true story, at least for plot like this. I'm a true alternate universe fan so I'm perfectly okay with stuff that doesn't have any basis. If anything, it's sort of selling yourself cheap by putting in a clause that shields you from people saying the premise is dumb. Again, the metric is whether the story is good or not, independent of everything.
The basics is that the people of Tehran were really worked-up about America giving asylum to a former dicator who ruled the place and oppressed the place and whose wife bathed in milk as the people starved, all for many years. This did not happen with Ferdinand Marcos and the Philippines. So the people storm the embassy, and I have to mention that this was really incredible camera work that raised my expectations so high, hold the people their hostage and film themselves saying cryptic stuff. But some Americans escape and no one ever tells the government that they've noticed white people looking lost and looking for a place to stay. The people of Tehran (generally) don't care about the leftist groups, I guess.