If you liked RE5 then I can't see how you wouldn't like this game. It takes everything RE5 did well (assuming you liked the more action oriented changes they made) and severely upgraded the controls and shooting mechanics. The online and voice chat seem to be flawless as well (unlike some games...looking at you FC3!). There is no way this game is a 3 or 4 out of 10 like some outlets gave it, or how Med just shits on it constantly after playing for two hours. The situation surrounding this game reminds me a lot of MoH Warfighter.
Jay and I have only played for about 5 hrs or so but so far this game is at least a 5.5/6 to me, not a 3 or 4. It's absolutely worth $20-30. Keep in mind that I buy more games than the average person so my price view point may be skewed differently.
Also, I'll let Dizzle speak for himself but I've enjoyed playing the co-op. I especially like all the crazy melee moves you can do in the game. They look like shit straight out of Wrestlemania. There is nothing like being swarmed by zombies to only have Leon power bomb the fuck out of one of them and have Dizzle shout "Oh shit son!"