Hah! I wrote that with the assumption that you've never played it. I usually assume that's what people want when they ask a message board about what they thought of the game.
I totally agree with you. It's in my top 3 best games on new gen systems and arguably one of my favorite games ever. I'm just a total sucker for anything that has to do with zombies, and this is actually something that has to do with zombies that's AWESOME! I'm leveled up at 50 and STILL playing this game.
I'm not even gonna try for all the achievements. But this game integrates the achievements well with the replayability. Heck, some of the achievements pretty much require you to play the ENTIRE 6 hour game through just to get them. But now I'm working on the punisher achievement (10 psycopaths killed), and the lifesaver(save 20 people). I'm dedicating this playthrough JUST for those two achievements. The next playthough I'm going for the Zombie Genocide (Kill 53,594 zombies!!!!!!)
Next game on my list to beat is Bioshock(waiting for it to come down to $24 not enough replay value in it for me to shell out more than that).
After that is Star Wars: Force Unleashed!!! That game looks SO sick.