From player's perspective, 7DRLs are usually good light games: they are very enjoyable, but you play them only for a short time. They are like movies or books (which also last just for few hours, and then you are enriched after you finish). It is nothing compared to very rich games like ADOM, which can be played and enjoyed for several years, but still, they are worthwhile in my opinion. The original ChessRogue was a great game IMO, although it was done in just 3 days.
Personally I didn't like Legerdemain... I feel that Roguelikes and IF don't mix, at least in this way.