I love the first two movies, and like Predators, but when i watch the movie i always think about the wasted opportunities. The main problem i have with this movie is how small and unimaginative it really feels. You're in an Alien jungle with dozens of creatures and prey from other worlds, yet, they do nothing with it. The jungle looks and feels like earth, there's one other creature in the movie for five minutes, the characters aren't terribly interesting. I actually love the stuff with Fishburne, giving some background on the whole thing, but it wasn't enough.
The concept was pretty interesting, but it really feels castrated for money reasons to the point that people say it's a pure rehash of the first movie and let's be honest, most of the homages just don't work, like Mombasa doing a Billy. The AvP's handled those much better.
It's still a fun movie and i revisit it from time to time, but it's a prime example of the case Shane Black is making at the moment, it was quickly assembled for a buck and there was no real creativity behind it.