Pros
If during the interview process you find the methodology and systems appealing, and can truly commit to them you'll have some great opportunities. The educational platform is excellent, and while everyone progresses through the same curriculum they do encourage that you play toward your strengths - great for the clients and great for the trainers (especially when working in a team based format) The diverging paths of opportunities appear a little while down the road, and while you may not get the exact position you want you'll probably be directed into a better one for your skills, or a role that will help you develop the skills you need for the role you really want. There's more to career progress than management - lecture, coach, athletic performance development, media, writing, public speaking, etc. Understand that the more you give the more you will get, and you need to prove your abilities at the basics before getting ahead of yourself. In short, if you(really) trust and enjoy the system as it's laid out it's a fantastic company to work for.
Cons
Some of the same issues as are present anywhere, to varying degrees of severity: 1) To be successful/viewed as 'good' you will need to be busy, and willing to accept additional responsibilities (without compensation) because 'there are just some things you have to do if you want to go further' (aka. you'll do this for free if you want to progress). While this is true almost anywhere, when it's put in blunt terms it fuels the following problem... 2) Expendability - following from the last point, if you won't shoulder the extra someone else will and you'll fast find any and all leads, opportunities and little perks disappearing from your orbit (this is something I mainly observed, but once I needed some time (after 3 years of 60+ hour weeks and working through my holidays) to deal with personal things it was made very clear that I wasn't a 'team player' and it was disappointing to them. This level of push does lead to considerable burnout rates, but with a revolving door of new hires in/unsuccessful trainers out it becomes uninspiring and morale crushing. 3) If you're good at balancing your finances great! If you're less than that, I strongly advise sitting down with another coach to set up a system that allows you to create a buffer - summer & other holidays can be lean times and mean the need to front and back load your clients to ensure stability in your financial life. 4) If you have your own idea about how to train, how to evaluate (e.g. that you don't like doing a functional movement screen/programming so you don't do it you'll have a deeply unpleasant time. They have their systems so 1000's of trainers can seamlessly change places and clients can train anywhere and everyone understands everyone else - that simply doesn't work if you're an island unto yourself and they will remind you of that. All the above said, the experience, opportunities, pros and cons are obvious, they're very transparent about what is expected of you to progress and for those who can commit their every waking hour to it you'll excel; if you expect however to coast or have a freelance client base on the side you'll struggle to keep pace and progress as you desire.