I just finished playing the demo, and I have to say, I'm thoroughly impressed.
You only get to play through 2 areas of the campaign Parish. You're in the streets of New Orleans, and then you venture to a prison, where, once you enter the prison yard, the alarm goes off, and hordes upon hordes of, well, The Horde come after you. There are more zombies than in L4D, and I like the varying appearances of the Special Infected; my brother pointed out that "the Boomer was a girl." Yea, it was. It looked like the Spitter from the CGI intro movie skinned over a boomer; ugly, pale girl with a green bikini top. As for the face, well, I didn't get close enough before I killed it to look.
I love the melee weapons. Absolutely love them. Machete is my absolute favorite, only because it's a one hit kill. They take the place of your pistol, which I don't care too much for, so the tradeoff is welcomed; you can still use a pistol, only when you've "died" and are awaiting resuscitation.
Speaking of resuscitation, I got my hands on the defibrillator, but my teammates never died, so I wasn't able to try it.
A bit disappointed in how short it was, as I was under the impression I was going to be able to play through all of the Parish campaign. However, it's a demo, so you've gotta suck it up.
L4D2 hits two weeks from today, which I'm going to be all over like stink on shit.
And GOW Collection.