Clyde has one and sleeps in it every night. He hated it at first and wouldn't go near it and now, when I occasionally take it out for a washing, he gets very, very angry at me.

I put a "blankie" (a washcloth) in it to catch poop so I don't have to wash it much; I just change the washcloth and wash IT.
Jade has a snuggy ring (it's a circular swing lined with cotton rope which she has chewed to shreds) and she likes it and sleeps in it, so I didn't get her a happy hut. She's got so much stuff in her cage now that I think it would make it kind of crowded, and she most definitely would object if I tried to remove any of her things that are there now to make room. Although now I'm thinking I'm a bad mommy for not giving her one since everyone else has one ...
The budgies have a happy hut, too, but they don't sleep in it. Benjy sometimes runs through it like it's a tunnel and somebody goes in there and poops, but they sleep on perches.