We have been workign with the eap-3660's for several months now and they are gaining in popularity.
I am finding that you can install one eap-3660 on the first floor of a building and cover several floors because of the antenna design.
Of cource you woudl want to use more AP' to load balance and provide the best experience but the coverage on a mult floor building is amazing.
There is more information on the eap-3660 here
Engenius Senao 600mW 802.11bg EAP-3660