Some say that AVP is silly and that the plot is thin, and they are right, but this movie is not about realism or story depth. Its an action movie where people are hunted by terrifying monsters and get killed without discrimination. This is a slight depart from the original Alien movie and Predator movie which had a more serious tone, so i understand why some may be disappointed by AVP. But if you expect a solid no-brainer action movie that entertains the viewers with suspense and action without taking itself too serious, then you get exactly that. It is a joy to watch all the right people get killed and the right people survive their encounter with the aliens and the predator. The main character is actually quite likable. Its not like in Prometheus, where you'd grow increasingly apathetic with each silly decision made by the characters.
Review of Alien vs. Predator
