I am really stoked to see that they made the game so much like an old school shooter. Health packs, armor. You can carry all of your guns, and LOTS of gore. They have added these touches to both the single player and the multiplayer. You can make plenty of xeno chunks when you hit a xeno with a grenade. I can't wait to see what friendly fire looks like in 'ultimate badass' mode.
Here in this video, at 30:05 you can see a melee shotgun execution on a xeno: http://www.ign.com/videos/2013/02/02/ign-live-presents-aliens-colonial-marines
There are numerous inside mandlble 'hole punch' executions done in the MP when they are playing as the xeno in MP. You are given a 60 point XP bonus when doing this. Also the xeno chops a marines' head off at 43:59.
With the way FPS games have been made for kids recently, I am really glad they didn't go the usual kiddie route with the game, and actually made a game for adults. I am pleasantly suprised how well this game seems to have turned out. I think this might end up being one of the best shooters ever. Maybe my favorite since the original Quake.