I'm finding the default controls a bit confusing.
EG. Space key is to open doors, as well as for using the "Snake Cam", which allows you to put a little camera under the door and look at the enemies. I've accidentally opened the door a few times when i just wanted to use the snake cam.
Also, you have to go through 2 or 3 menus before you can equip a grenade to throw.
I've only played it for about an hour, maybe i'll get used to it.
Gameplay is good though, fun.