I'd like to say first off that a lot of the problems with the servers for this game have already been ironed out, many reviews were extremely premature as anybody with sense knows that many games which focus heavily on multiplayer mode will have teething problems.
Onto the game itself now, SP mode in FPS are secondary to the MP, if you want a deep and complex plot then you shouldn't be looking to FPS for the answer, with the possible exception of Half-Life 2. The whole point of these games is action, and that's precisely what you get from Bad Company 2. The SP is action-packed, exciting and challenging, but serves only as a taster for the meat of the game which is undoubtedly online.
Now for the multiplayer, which provides 4 distinctive game modes, Conquest (Essentially Domination to CoD players) Rush (Which involves the attacking team destroying strategic points on a map thus forcing the defenders back to other positions) as well as two squad game modes including a squad deathmatch. An absolute deliverance is that unlike CoD, you can choose which map you want to play on at any time. With a series of enormous maps, a wide variety of weapons and 4 player classes to choose from, from Assault to Medic, from Recon to Engineer there is something for everybody. It wouldn't be Battlefield without vehicles, again there is a wide variety on offer, helicopter gunships, heavy/light tanks, IFVs, humvees, quad bikes and assault boats, even a UAV you can control and spot targets for your team on the ground or guide missiles to targets yourself.
The real differences between this and Modern Warfare, is that MW is more of a blisteringly fast skirmish, this truly is a battlefield, with large open spaces, buildings, plenty of cover, as the terrain plays a key role. Bad Company 2 also massively encourages teamwork, too often on CoD, players would run off alone and never be seen again, with the classes available teamwork is a necessity.
For example if you are driving a tank and it takes damage, it isn't at all uncommon to see another player who is an Engineer run over and begin repairing said damage. He gains points and you stay alive. The same with Medics, they are encouraged to handout med-kits and revive fallen comrades for points and to save the tickets your team uses for every life, it all creates a real feeling of teamwork. Many vehicles are also best utilised with other players, upto 4 people can enter an IFV for example, one driving and operating the main cannon, another the heavy machine gun and 2 others using the side windows to provide cover. You simply can't play this game properly by yourself.
Graphically the game is fantastic, I wouldn't say in every way superior to MW2, but it has an authentic feel about it, when you fight on the desert maps for example, very often the wind will carry clouds of dust and sand which will obscure your view and the same goes for the snow. It feels like a real battlefield and not a symmetrical square no bigger than a football pitch as in other FPS.
The rank system is challenging as you must work hard to gain enough points to advance, new weapons and perks have to be earned through hard graft, they aren't just handed to you. There are many insignias and pins to aim for as you complete various tasks and achievements along the way.
All in all this is a quality game, I recommend you buy it new as you will receive a VIP pass to gain access to two additional maps which you would otherwise have to pay for. This is a quality game which comes to life online, it's a more mature, sophisticated and challenging first person shooter, and most importantly, bloody good fun.
I am trying to think of a negative that I can put into this review to give a balanced opinion, but I really struggle to find one, perhaps some will be disappointed by the SP mode, but if you expect action and excitement you won't be. Any instability with servers has largely been eliminated and further updates are upcoming. There are just far less problems to contend with in game, the knife isn't absurdly overpowered like in CoD, camping is less of a problem on maps which are much larger, it's nicely balanced, the maps provide different challenges, and the squad system....just makes sense.
I doubt the vast majority of even casual FPS followers will be disappointed. I hope this review helps you decide to purchase this fine game.