It's a pretty good game overall. Just a few issues involved with it that makes it so it doesn't deserve a 9.
Though, the actual online games are some of the best you can come by. With the new versions instead of strict kill the enemy, you have objectives and a lot better missions making it so much more entertaining.
A few more good points are the combat system. It is fast paced and well worked out. You can aim precisely using both the infected and survivors. Another amazing addition would be the new infected, jockey especially for me. They make playing as infected even better than before, and that was probably my favorite aspect of the first. Great controls, great ways to fight the survivors, and amazing dynamics.
Overall, buy it if you play online a lot and that's what you want. Otherwise, it will be a complete and utter waste of money.