So folks are talking about this vs. MW3. One of the things I enjoy most about the COD/MW franchise is that it's a shooter/arcade style game. That's also part of what makes folks mad, the fact that it takes 3 bullets (or more) before you die. I'm not condoning that part, but the arcade look and feel of that game is the total opposite of this game. BF3 feels like something used to train military. It's chaotic, it's heavy on strategy and team, and unless you're into that kind of thing, I think online may not be real appealing. One of my biggest gripes about online was that you can't carry two "primary" weapons, at least not from what I saw. You always have a pistol as a sidearm and even though it's more effective than the pistols in most games, it's still disheartening that you can't pick between a rifle and a machine gun etc.
The single player campaign is great! I enjoyed the storytelling and gameplay a lot but the real part of shooters that I get into is the online play, and without a squad that is on with you whenever you want to play, this game doesn't have much replay value to me.
I decided to pay the $10 to play online, I've saved enough money by using Gamefly so I figured it wouldn't hurt. It's a lot of fun, but only being able to bring 3 of your friends with you can make the game tough. It's rare to find an entire team working towards the objective. And trying to get people who aren't in your squad to give you ammo or health is a pain, it seems no one pays attention.
If you're an online shooter fan there's a lot you can like about this game. But there's also complaints you'll have. They're the same things we've been complaining about in every shooting game.
I think this is a game you could enjoy for a long time. I'd wait until MW3 gets released and you can read some reviews of that to get a better understanding of which game you'd prefer.