Picked this up on special and it's the most co-op fun I've had with friends since Borderlands.
Grenades and explosives are some of the most satisfying to use in gaming, especially when you can chain a bunch together. Graphics are nothing to write home about, but it keeps up pretty well with all the carnage being wrought. Some of the set pieces are intense as all hell, and you really need that quiet moment after them to scout the areas looking for hidden bottles before gearing up and moving forward. The games synth score rocks too.
Through settings you can really make the game old school hard. I play with 2 friends and we sometimes ramp it up to the level for 4 players. On the harder difficulty zombie snipers go from being a minor annoyance to priority kills that you need to take out quickly.
Definitely worth giving it a go with friends, and I hope the Sniper Elite team make another one.