The museum itself is pretty nice and I do mean the museum itself. It is a very impressive building. As for the exhibits, they are interesting and fun (i.e. a walk through time in Georgia a.k.a. a history of the world with a southern influence). There are also lots of interactive activities for kids.
But most fun for me, was the IMAX theater. You can see several IMAX shows at any one time. And in the summer you can enjoy martinis at Fernbank. You will hear live music while you drink, mingle and wait for the next show.