Pros
Opportunity for advancement is good if you don't get burned out within the first 6-12months. The training school in Ft. Worth is very good imo. If you don't have a college degree, the school will be a bit more challenging. Your manager will want you to breakout as soon as possible, so you need to absorb and push your mentor(s) to allow you to do tasks to help you learn and advance.
Cons
Typical oilfield atmosphere, make sure you have though skin. Long hours, if you have a family prepare for this. Random work days, some JFE's get put on a schedule and some do not. Your manager wants you to get in as much experience as possible, so you will be catching a lot of jobs. Compensation, you essentially do the work of an operator and an engineer when on the job, so the work can be frustrating especially knowing you're not being compensated as well as the operators or engineer on the job. Sure your salary when broken down to an hourly rate of a typical 8 hour day is decent, but the hours you put in will diminish your hourly rate to that equivalent to those flipping burgers. Some districts I believe get field bonuses for JFE's, so request that in your interview and make sure it's in your contract...and if it is in your contract make sure you get paid!