The gameplay looks interactive, but it won't last long the boring once you have finished the game.
Single-player:
The campaign is surely short, but you can choose some difficulty which can be easy or veteran (expert). Though I'm not very competitive. It's up to you what kind of difficulty you want to choose and feel the experience of the gameplay.
The music can be sometimes good, but I've just turned off that I deleted a file. The voices of the characters sound pretty good, even Captain Price and Cpt. McMillan. Although the AI can be sometimes stupid but they look good the animations to me.
The multiplayer: (requires a punkbuster installed)
If you like to slaughter some players, this is your type of your game, if not, you'd better not get addictive playing this game, because it was really damn addictive and I couldn't help playing like 2 years ago. Here you can customize your own class once you've leveled up at 4 or 5, I don't remember well. Long story to tell this.
The gameplay and the perks didn't intrigue me a lot, some players can get any idea to achieve the game of the multiplayer such as camping, using a perk so-called Martyrdom that they toss a grenade when they're killed, if luckily, an opponent is toasted by a grenade that the player's dead, the grenade launchers and the last stand, when a player is dying, he has a second chance to use his pistol in 30 seconds.
At the end, I felt pretty addictive, pissed off, too. I've stopped playing and thought that this game is getting fed up and bored, plus, you may or not have "friends" chatting around when they're shootin' around.
I didn't get any "friends" of those players, though. It was lifeless.
Although, if you've got a guy who plays call of duty 4, play a LAN or thru an internet. I think that's it. A 7,5 would suit my opinion. I may want to shoot around and have a little of fun, but FPS is not the genre that I don't like it so much, such as battlefield, CS or TF2.
If you feel ashamed or something you've got addictied, feel free to play another video game that doesn't have to do with first-person shooter video game.
P.S.
There's also an option you can use some mods, as far as I know, there are some mods such as Reign of the undead 2.0, the CODJumper, Obscurity and so on... (the first one looks good, but the rest are uninterested, if you want to mess around with those mods) Look up through gametracker website to see more servers on your own country.