I agree, Kas is defintely one of the nicer areas to dive in Turkey. Also, the village is very, very nice and has banned the large scale touristic development that is ruining the charm of places all along the Turkish coast.
Here's a PDF of an article I did on the place for a Dutch diving magazine.
Great atmosphere, no big hotels or large resorts, friedly people and a very layed back style of diving. Plenty of great places to eat or stay though. If you have some time, rent a car and drive around the beautiful countryside.
www.kas-diving.com is a great operator to go with. The owner, Levent, is a superfriendly hyperactive guy who has a great way of doing his briefings (a large towel is involved).