COD4 was a very good game but I only recently started playing it. I would say that balance is the key issue for making a great COD game. In my opinion Black Ops was the best COD bescause MW2 had the noob tube problems and commando knife. If those things were not in the game it would have been the perfect game. People complain about ghost in BO but it wasn't a serious problem just annoying. I didn't run ghost and used the Galil as my favorite gun over the Famas and had a 2.47 K/D in BO. It was balanced and didn't have the BS included in Infinity Ward games. The strong players dominated and the weak players suffered, so there were a lot of complaints. That's why MW3 is so noob friendly now, the people that sucked who stopped playing BO got back into MW3 and now even more players that suck got into and they wanted a easy transition into the game. That's why Support is setup the way it is, deathstreaks, and why they made Assassin Pro so overpowered.