Never owned one (did won a '17) but flew several different ones.
Pluses: Handles great, climbs well, limited water ballast capability ( "As" had bags put in by many owners - standard in the "B" model), holds value, assembles easy and the factory will still support it. Integral roll bar at rear of canopy frame. Well documented performance. Most of Part 2 of Reichman's book uses the '15 data.

Negatives: removable canopy (PITA), balsa core wing construction (susceptible to water damage), off-center CG hook (eliminated in "B" version) plus tail skid can lead to trouble on take off (groundloop).

There is an old AD for wing spar internal inspection on these and similar vintage Schleichers - probably complied with.
Good luck.
ROY