It's worth the $60, even if it is a single player game. The story is genius. Beat it once, beating it again in 1999 mode to get 100% achievements.
From what I heard, people's brains crashed midway through the conclusion. So be sure to collect and listen to as many voxophones as possible. Give yourself a moment to compile all the information in, and let the game fill you in. But most importantly, have fun.