Been playing this a couple of days now, and i must admit the first hour or so i really didn't like it, i didn't know the maps, and i just wasn't used to it. (Got killed a lot) and i'm not used to that on cod4 being 10th prestige and a kill ratio of 2.8 :)
But that's all changed, once you get used to the weapons the maps and how people play, it is a great game, good perks, weapons, bigger better maps than cod 4 but a little slower paced. Also it's good to see your legs and arms getting blown off on the kill cam
I also noticed one of the perks doesn't unlock until level 65 (flamethrower) and the more prestige's you do the more custom slots you get to create your own classes, so this time round it pays to prestige.
So if you can get used to ww2 weapons and like bigger maps i think you will enjoy this as on online game.