The entrance to the cafe is a bit underwhelming if you arrive when the bookstore is closed, but the cafe itself is beautiful. I only wish the chairs were more comfortable, because the place simply invites you to spend a lot of time in it.
The service is good, the cakes are very tasty and huge (try the Dobos cake - it was great). Prices are a bit higher, but nowhere near some other elegant and outrageously overpriced Budapest cafes. The service charge is included in the price, so no need to double tip.