It's new for you and kinda new for us too - but we get to actually play it. The coop hasn't been in for too long and while split screen have been in for a while, this is the first real test of it.
Me (Hipshot) and level designer Eric is playing the mid-game Troy level, it's a kinda tight level with a lot of corners and twists. This level also introduces poorly camouflaged enemy snipers that waits around for that 1 shoot 1 kill opportunity!
Also, just recently the step towards a proper play through came in, with the ability to complete a level, load the next one and keep whatever weapons and ammo you find. The first proper Singleplayer run took a little more than 1h for the first 3 levels, which is fairly good I must say - since we are lacking a lot of time taking features like bosses and some larger enemies!