I just finished this game -- took a little over 9½ hours.
Oh, hell yeah -- Best Shooter of 2006.
About The Ending Portion "After The Credits"...
[spoiler]
I think it's a mistake that many movies, games or works of art leave a CLIFFHANGER before The Credits. It's annoying -- as it feels so incomplete. Prey's story is complete, so they throw the credits at the RIGHT TIME; when the story is complete. Nothing left hanging here, so throw the credits now....
I think if there's a planned cliffhanger, it's something they should sneak in, if they do, AFTER the Credits. It feels more like a preview or a trailer to the next piece, if you ask me.
So, I do like how AFTER the game credits, they basically begin what will probably be a Prey Expansion Pack or probably, which is a lot more likely, a Prey 2.[/spoiler]