Great game, you have to try it.
What I really like with Resistance: Fall Of Man, is that it features a great arsenal of the weapons and the AI of the enemy. My personal favorite weapon is the standard machine gun. The multiplayer is great. It got great potential and really easy to just quick start and join a game.
Though, this type of gameplay isn't that new-thinking, world war 2, aliens trying to erase mankind. I'm in person, isn't a big fan of WW2 games. I'm more with the modern type of style ;)
If you like FPS games, you should definately go for Resistance. Let's see what the sequel will be like. It is worth playing.