I've started going to yoga classes, and they're really quite good...all the other failings (both my own and those referenced below) still hold true, but I'd give four stars to the instructors. They are extremely nice and put me through a great workout, but they too have to deal with crappy operations (insufficient and worn out mats, an inaccessible sound system, temperature issues, etc.)
Unfortunately, in my math, that only translates into two stars for the gym, which is still "extremely bad" fitness, just marginally less so.