Yeah, you need to play it with other people, and most importantly with decent people. If you land up with someone who is just going to run and gun, not wait for team, and get himself killed constantly it can ruin it a bit.
Never played a game which was so entirely dependant on the people you play with.
I was skeptical about the game, but after having played for so many hours last night and not even completing the No Mercy campaign, I can see this game will be great value for money, and don't think it will get old quickly as I feared.