Avantages
They make sure you are compliant and don't have the state board knocking down your door (unlike some chiropractors). The corporate training is pretty good. If it is your first job out of college and you don't mind working a lot for a small salary and you go into it knowing their promises to sell you the clinic will not happen, then it's not so bad.
Inconvénients
Have a lawyer review your contract and be very careful. They will screw you. If they promise you that you'll be able to buy your clinic, you won't unless you want to pay three times the value of your office (which you won't be able to get a loan for). If they promise that you'll make a certain amount of money, you'll probably only make your base pay and perhaps just a little more. If you are okay with your base pay and you don't care about buying the office and you are okay with being forced to work every weekend doing screenings at fairs, farmer's markets, flea markets, etc, then you will learn something while working there.