I've been a member for four years and find rowing to be a great form of exercise and lots of fun! Rowing with a team of four or eight requires a lot of discipline and training to do well, but that makes it an interesting challenge. At the same time rowing a single allows you to work on your own and enjoy quiet time on the lake (which is beautiful). Racing at regattas such as the Nationals at Greenlake this summer are really exciting. A membership allows you to take boats out on your own (singles, doubles, and pairs), but you don't have to be a member to take classes.
Pros: exercise, fun, equipment
Cons: time-consuming, can be crowded