I used it to purchase Memories of the World Tree (
http://vgmdb.net/album/20464). I actually used it the day after they made it available, and it was prompt and easy. However, you wind up paying a middle man fee, the shipping to them, and then the shipping to you, so it is rather expensive. It's reasonable so far as middle man services go, and I like having a middle man that I know I can trust, but the exchange rate between the dollar and yen is pretty bad at the moment (76.9 yen per dollar), so you might want to wait a while.
They do offer reward points based on amount spent, however, so perhaps buying now wouldn't be terrible in the long run.