Lego Batman has its bad points, but it is definitely enjoyable at times.
Unfortunately, it is somewhat darker than the other Lego games. The humor, although funny occasionally, was pretty dumb (but Batman looking at awesomecapes.com did make me laugh).
One of the good points is that you can play as the bad guys, and if you listen carefully you can hear the Penguin quacking.
The ability to use the Batarang as Batman, Robin, Batgirl, and Nightwing is fun, and Catwoman gets her whip.
The thing I really hated was the vehicle sections. Having to continuously collect mines and then turn in such a way that the mine will swing into an enemy boat with around 10 hearts is not exactly enjoyable.
So, although this game is not as much fun as Lego Indiana Jones 1 and 2, it is fun with a friend and therefore worth buying.