Certainly not a bad game, but the technical issues render it much too frustrating.
First of I couldn't even launch the game at all, whether it was SP or MP, and 3 months of online support didn't change a thing.
Couple of months later I downloaded the 1.2 patch, which allowed me to launch the game, but I had no sound. Again, online support didn't help, and the solution they gave me was for Windows Vista only. I eventually got it working (thanks to the help of an online forum, not online activison support i might add); thing is before I can play the game I have to, every time, go to the configuration panel, and remove all Modem entries, which does get frustrating pretty quickly.
Once I started the game itself, it was nice enough, SP campaign, albeit short was interesting, if sometimes squandered with occasional frustrations. But I had a strange feeling while I was playing, which quickly became the uneasy impression I had already done this before. And indeed, though the setting was different, it really was the same structure as Cod 4; the campaign also lacked a decent length, just like Cod 4.
Then I tried my hand on the internet, which was fun setting aside the issue I had with power leveling servers, which allowed to almost instantly reach maximum level (where's the challenge). But again it played almost exactly the same as Cod 4, the only difference was the setting and the weapon skin. I also quickly noticed two main problems with MP. First it was the loading time were ridiculously long for me (and near instant on Cod 4), sometimes reaching 5 minutes at lowest configuration settings, and second that I got disconnected at the end of every MP game (I even had to leave the game and start it again before I could join another game).
As far as the gameplay is concerned, it is as I said almost a WWII Cod4, only slight changes prevent it's complete similarity, though those are really small, such as bayonets or flame-throwers. Nazi Zombies mode is amusing, but just don't expect much from it. Co-op however really stands out, I had some endless fun while playing it, a boring SP mission can become a frenzied rush to get more kills than your teammates.
The similarity does come with drawbacks, beyond the feeling of déjà vu, for instance the weapon recoil is still ridiculously low, you'll run straight ahead of you, all the while shooting a Ppsh with almost 100% accuracy (my grudge with this is because i'm a Red Orchestra player).
The reason why I gave this game such a low mark is that I find it inexcusable to release a game that doesn't even work on most computers, and later releasing a patch that makes some computers, which ran the game just fine, have problems with it (1.2 patch removed the sound on many computers, as I've heard)