Expansion packs only sale for $7.50 and worth it.
As good as Battlefield Bad Company 2? Not quite, but that game is older, and BF3 ups some of the graphics and immersion, whilst falling behind a bit on destructible environments. Biggest drawback is the sometimes weak hit detection, which isn't quite up to par with BC2. The developers have at least maintained a commitment to keeping the game up to date.
Graphics also are worth a mention, definitely better than anything I've ever seen. Stunning. Spectacular.