- Some of the new zombie classes work well. The Spitter is a neat idea although I guess the acid would have to be just temporary since most maps probably won't have optional detours or shortcuts. The Jockey is, by far, one of the best new zombie classes. It's really effective at quickly steering you away from your party and off a ledge or into a horde. The Charger... meh. It's a combination of a hunter in that it grabs you and you can't get free without help, and a Tank which charges in and incapacitates players.
- Speaking of the Tank, that thing has seriously been nerfed. Several times I almost single-handedly took it down and I usually get chased down and stomped flat by Tanks. It seems to have maybe half of the hit points from the original, and that's after the original was also nerfed.
- There's not as many hunters/smokers/boomers as the original. I guess that makes sense since Valve had to make room for the new zombie classes, but the new classes just aren't as effective as the originals. I ran around everywhere with melee weapons, hunting down zombies and taking them out, and wasn't really worried about a Hunter or Smoker crippling me until my teammates could help.
- Speaking of melee weapons, those are fun. I used a chainsaw, a sword, and something that looked like a cricket bat. Problem is, the melee weapons make it way too easy. Like I said above, I ran around with impunity armed with a sword. Each swing takes out 2-3 zombies at once. That's not realistic. Better to have maybe a swing take out one zombie, or more realistic yet, have some melee weapons more effective than others (they all seem to do equal damage except for the chainsaw), like a sword or axe could behead a zombie with one swing, but a bat or a crowbar would take more than one and thus wouldn't make a good primary weapon. But the way melee weapons are implemented now makes the game way too easy.
- More on melee weapons: you can either have a melee weapon or a pistol. That was very confusing to me at first, because at the start of the mission I had a pistol, picked up a crowbar and the on-screen hint was telling me to hit the Y button to change weapons but I could never switch back to my pistol. I even paused the game and changed controllers, thinking that the Y button had suddenly stopped working.
- There seem to be more explodey things in this game. Many more gas tanks, propane tanks, and oxygen cylinders. I took out a Witch by tossing a propane tank at her and shooting it. They're just lying around everywhere.
- Speaking of the Witch, she now walks around instead of just sitting in one place. That's a nice twist I guess, but what it really means is that if she's blocking a pathway that you have to go through, whereas before you'd just suck it up and have to startle her, now you can just wait until she walks away.
- Maybe in an effort to offset how easy Valve made the game, first aid kits now only restore up to 80% of your health. So that makes it more challenging, not that I got down that far very often. There's a new health boost too: adrenaline shots. They temporarily boost your health and supposedly also increase your speed, although I didn't notice a major difference after using one.
- The first mission is more complicated than the straightforward "kill the zombies and get to the safe rooms" of the first game. There's more climbing over things and less taking direct routes. Here Valve could've made the game much more difficult by providing more than just a scattering of zombies in each area, but they didn't.
- There's also two twists in game flow for the first mission: first, you have to go and fetch a pack of Coke from a convenience store in order to get a gun shop owner's help in continuing to the end of the mission, and then you have to run around and find 8 cans of gasoline to fill up your escape car. The Coke fetch was novel and again could've been made much more difficult by adding many more zombies than I saw, and the same thing goes for the gas can fetch, which was made way too easy by 1) far too few zombies, 2) far too many available gas cans, and 3) visually highlighting the locations of the gas cans so you don't even have to hunt around for them. And there's also extra first aid kits and an ammo stash right by the car that you're gassing up. It's almost as if you're supposed to survive.
- I almost forgot to mention: there's an area early in the mission where you have to make your way through a burning building. The graphics and experience for that part were very, very well done.
So overall it's still a fun game, it's got several new twists that do make game play more interesting, but speaking as someone for whom "normal" difficulty on L4D1 is still somewhat challenging, the "normal" difficulty on L4D2 felt more like the easier end of the "easy" setting.