DS8 attended Epsilon Camp last summer and we plan to have him attend again this summer as a 9 year old. He absolutely loved it. The math was almost all new to him (Euclidean geometry and proofs) which he thought was great! The camp is 2 weeks and parents have to stay overnight with the kids...it is not a sleep-away camp. DS's comment was that he learned more in a day than he learned all year in school.
He also attended SIG last year and the year before (day camp) and he liked it, but it was not challenging the way epsilon was.
Kate