I have spent YEARS trying to find something that works well, looks good, and most importantly is easy for my clients to use. PhocaGallery has been the best option, but it has still had its issues.
This is so awesome because it doesn't do anything except embed your existing Facebook galleries. Why have 2 separate galleries? Why upload photos twice? Facebook already has the best user-managed photo gallery system available, and this allows the user to work with their photos in an environment they're already familiar with, and have them available on their own website automagically!
I'd give it 10 stars if that were and option. Best $20 I've ever spent.