This is the movie that started the Alien Nation franchise, with a TV series, and another 5 movies. It's a cop, action, thriller movie - with aliens.
Alien Nation isn't as well known as many similar sci-fi series of the era - and this is the start of it all. Although this uses different actors than the subsequent series and movies, but it does have all the distinguishing traits for the follow-ons. Characters with depth, humanising of aliens, the examination of racism and bigotry in a way that is surprising for entertainment from this time.
And as such, for any sci-fi fan it should be on their watch list.