Prey=Half-Life2+Red Faction+Doom 3, and a great combination
Although the story line is weak, the little bit of voice acting is fairly solid. Also, if you need drive to get through the game, the achievements are pretty easy, as you gain one after each level, then one at the end of the game, and another 65 pointer after you defeat the game on Cherokee mode.
The control in the game is about as solid as controls in an FPS can be. There's a bit of auto aim featured, which really helps you get the head shots, and the weapon switching and other controls work well, not really much to say there. Prey is a bit lacking in the weapons department. It's got some cool ones, but could use a bit more destructive power, or maybe just a bit more variety. The ammo placement in the game is very well designed. You'll never run entirely out of ammo, but you'll come close a few times towards the end.
The environments are absolutely wicked. With high detailed environments backing up some beautifully creepy rooms and hallways, in addition to some absolutely gigantic parts of the ship when you're flying around, it really sets a great atmosphere. Some parts are pretty disgusting, too, like a hole in the wall that looks like a giant anus that opens to form a doorway for you, even gives a nice sound effect (your character voices his disgust the first time he sees things like this). The enemies, like the guns, are a bit lacking in variety, but the few there are look pretty friggin cool.
Some wild stuff exists in the game, like magnetic walkways that allow you to walk around on the walls and ceilings (these also provide a good strategy, as you turn them off while enemies are on them, the enemies fall to their deaths!). Then, as there are a lot of Half-Life 2 style puzzles in the game, there are spots on walls and ceilings where you can shoot to set the gravity onto that wall, to get around high obstacles and whatnot. After a certain point, you can also enter the spirit walk, where you leave your body and can not only walk through energy fields to flip switches and turn them off (although you can't open doorways in spirit walk), but there will be hidden walkways that are only accessible in spirit walk. You also cannot be hurt while in spirit walk mode, but you can shoot from your spirit bow, which gets replenished when you collect souls from dead enemies.
One possible major down or major upside (depending on your personal preference), is that the game is VERY easy. After you get passed like the second chapter, if you ever die, you go to death walk, which is where you get about 30 seconds to shoot these death wraiths flying around you to replenish your health. If you get just 1 red death wraith, you get to return to life right near where you died (unless you were in a transport vehicle), and keep going. When you beat the game and play Cherokee mode, you'll be shocked at how the difficulty doesn't really go up. I think all the enemies stay about the same, but you don't get any health power ups, which only really hurts you during the second chapter when you can't access the death walk yet, but it's not that hard. I think I actually died less during Cherokee mode than my first time through!
Achievement-wise, just play through twice (once on each difficulty) to get, I think, 740 points. Each play through is short, only about 6 hours, if you take your time. There are online achievements, but I didn't play much online. Playing multiplayer, there are some pretty cool strategies with the gravity walls and such, but you'll have more fun with bigger named fps' online.