Skip the single player and head straight for online!
Battlefield: Bad Company is a great game. The multiplayer is deep and rewarding and even with one mode, it offers lots of lasting enjoyment. More on the multiplayer later. When you start the single player side of the game, the flaws are obvious.
The most problematic portion of the game is the artificial intelligence both for your squad mates and your enemy. While moving from objective to objective, your three other squad mates will lag behind, waiting for you to engage the enemy and when you do, they will shoot at anything that isn't an enemy solider vehicle. It isn't a stretch to say that combined the three of them killed 10 enemies through the entire game. You're enemies aren't much brighter but they can hit anything they choose and the choice is you. The other enemies completely ignore your squad mates and pummel you with rounds at every opportunity. They must have got the memo that your AI companions were going to mail it in through the entire campaign.
The graphics are also on the poor side during the single player campaign. The particular geographical setting (mountainous eastern Europe/Russia) leads to a lot of the levels looking the same and they all seem to run together in one long-never ending skirmish.
One of the most annoying part of the game is the respawn mode. When you die, you respawn at the last checkpoint but nothing has been reset. Enemies you have killed prior to dying are still gone as well as vehicles. This also means your vehicles and your ammo. Many a time I would be destroyed by a tank in a tank and then have to hoof it back about 3 minutes to where I was terminated. Also, I would run out of ammo (there are so many guns in the game, you hardly get resupplied without going out of your way to look for it) and be forced to take a enemy position using a grenade launcher and a knife, not fun.
Well, back to the good stuff. All of these problems disappear in the online modes, the AI is replaced with humans, "kits" which supply ammo are all around and the vehicles you can use respawn frequently. All of this leads to an intense war-like experience online.
So, forget the single player and jump head first into the online world of Battlefield: Bad Company.