I'm sure I'd enjoy Borderlands 2 if my friends played with me like they said they would when it was first revealed.
i can assure you that with any number of people besides yourself it is much more fun
yourself (w/no one else to play with): no fun, only satisfaction in beating the game by yourself (if you manage to)
yourself (w/someone to play with but you aren't playing with them at that moment): fun because you over-level them and get cooler stuff to brag about
you + 1 person: coordinate your plans easier, isn't hectic but you get through the game faster = more fun
you + 2 people: might be a little out of control but that adds the fun aspect of failing occasionally and the hilarious moments you share with your friends
you + 3 people: absolute party nothing goes right people get mad at each other while also you laugh at each other and the game will last you much longer and it's fun and it's fun and it's fun. (recommended)