I liked Prey, had interesting weapons, an interesting change of characters and gave me a real sense of how "alien" aliens could be. I really liked the portal and gravity changes and how it forced you to think a little differently. I personally thought it brought enough to the table to be a fairly good game but alas most people disagree.
If they make the character just another blank snooty space marine and/or remove all the cool gravity and portal puzzles, I'll be very unimpressed.
Why aren't there any other games (that I know of) that use the same portal mechanics that prey does? I know Portal does and there are a few fanmade maps out there for other games that have the right engine, it seems like a waste of a really good game mechanic, especially if you just have the base have 5 90degree turns to end up where you are or something, so not using the portals the same way Portal does (capitalization counts here!), but more like those multiplayer maps.
Wow, just realised how off on a tangent I went.
Prey 2? Probably buy, depends on if it uses the same engine as Fallout3/Oblivion, I doubt I'd get it if it used the same one as Skyrim because it almost certainly won't support all that fancy portalling technology.