Alien vs Predator Omnibus consists of two compilations: I & II, each with around 450 pages.
The first volume includes seven compilations, exploring from a classic human-colony-gets-attacked-from-both-alien-species or a futuristic human predator hunter, to quite a few stories showing us more details about the predator race (don't want to enter into spoilers territory). They feel fresh, different and some continue ideas and characters presented on previous ones. I really liked this volume.
My problem came when I started reading the second volume. At least half of it consists of the series "Aliens vs. Predator: Deadliest of the Species", a futuristic tale involving Aliens and Predators, yes, but way too bizarre for my taste. I tried to follow it but goes too much into dreams and other storytelling techniques that, combined with an uninteresting story (to me, at least), made me skip all of it. The remaining contents are a few more series, some of them really brief (4 issues with few pages per issue), so you'll get mostly short stories. Some of them are interesting but overall don't justify purchasing the whole book to ignore half of the contents...