Pros
I've been with the company for several years, and I can say that this position is forced me to grow in every way. The commissions and bonuses are tiered, so the more you sell the higher percentage you were able to get. So top performers can make a lot of money! And from my experience, the personal trainers that we hire I've been fantastic, and if they are not, they get managed out and we quickly replace them with someone better. But it is largely up to the individual training directors to set the culture at their club. There is also the opportunity to travel if that something you were interested in.
Cons
This job is definitely not for everyone. You need to be driven and have a strong work ethic. And you have to be passionate about fitness and what you do, because in a full-time position there are definitely weeks when you need to put in more than 40 hours. But to me the majority of the time, it doesn't feel like work. And again, because the commissions are tiered, if you are not bought into the culture and don't perform you probably won't be happy with the pay.