Agreed. Though RE6 is a hard-sell for me even with the co-op. Me and my brother played through it and got frustrated with the game frequently (Leon's campaign was alright at least).
"fun with friends" is no kind of compliment at all. if two people are good enough friends they can have fun watching paint dry. that said, RE5 and 6 are technically decent games but as a part of a series with such abundant quality as RE they feel a lot worse than they actually are.