I'm Jewish and I use one on sukkos. They smell amazing, better than any other citrus fruit, and the entire tree (stalks and leaves) carries the same perfume. They aren't much to eat though. There are various slightly different types that are traditionally believed never to have been grafted and most are almost entirely pith. They make nice jam but I've always been too scared to make my own - they are so fragile that apparently the growers use obscene amounts of pesticides on them.