Great game with big variety of levels and guns. Only graphics could be a little better, especially explosions.
First few levels are similar to each other, but when action takes part in other places, one word we can say is "WOW".
We will fight in caverns, metro tunnels, and even on a alien small ship. Most atmospheric level is cavern - our flashlight gives small light and enemies are hiding in darkness.
This game is not so long, but not too short. It takes about 6-7 hours to finish (I'm medium skilled player, not a hardcore).
Good sides :
- variety of levels
- reasonable difficulty level
- lots of guns
- great atmosphere
Bad sides :
- graphics (especially explosions)
- small number of enemies
- only few bosses
- a bit too short
Summarizing, this is a very good game, with lots of positives, but it can be too short for hardcore players and too hard for "easy" players.