Pros
The only pro is that you get as free gym membership and the other employees are generally pretty great. There is some room for growth, but growing in this company is not worth it. You either don't make much more or make LESS. For example, you get paid minimum wage at the front desk and from there you could become a personal trainer or sales rep, but both of these are almost purely commission.
Cons
Expect to get paid like a waitress, treated like a car salesman and expected to dress and look like a celebrity. Although co-workers are awesome, most management is awful and fairly evil. The trainers don't know what they are doing and aren't given enough experience before being hired. The management does give the trainers "training" once a week for the job where they essentially just take the trainers into a room and yell at them for sucking at their jobs for a couple hours and explain creepy tactics for forcing people to be your client. Additionally very little time for breaks. If you are a trainer expect multiple phone calls if you aren't at the gym for more than 2 hours, even if you worked a 12 hour shift (without pay) because why should you be doing anything else when you could be finding clients??