Yeah I crumbled at the good timing of the 25% off. Not played all campaigns yet but so far better than the demo. I'd agree with the upped difficulty, normal is more like advanced in L4D1, even allowing for less knowledge of levels.
Though not as bad as the demo, movement and aim feels a bit... Sloppy, bit like bad fps & ping lag but they report fine (though get drops on Hard Rain?). Going to try stripped down graphics see if it gets better.
So far overall I still think L4D is the better game (just seems... more carefully thought out or something) but yeah had some good games and bringing out the chainsaw when there's a horde rushing down a tight corridor was just as fun as it sounds.