A fascinating exploration of a culture clash. What's great is that each of the main characters gets proven right in some way, even if it is ultimately horrifying. The movie also doesn't play with simplistic stereotypes as everyone feels totally real.
Sort of a greatest hits collection from Emmerich (The movie is filled with repeated beats and characters from his previous movies, i.e. the crackpot who was right the whole time, the gleeful destruction of cities, etc.) but the problem is that it kind of runs out of steam at the exact point it should get more exciting.
The movie is definitely underrated (it is mercifully short for an epic and despite its reputation, this isn't all that campy) and probably deserves more respect than a lot of other similar films from this era.