Pros
The best reasons to work for FINRA are its benefits and its work/life balance. Depending on your location, you may also "luck" into great management, but some locations and/or departments have questionable leadership. Co-workers tend to be wonderful people and most people understand the goals of the organization and really appreciate the importance of the work they are doing. It is a nice balance between government work and industry work -- pay and benefits is higher than government work (although not close enough to the industry's standards), while the work/life balance is closer to what is expected of governmental employees.
Cons
Pay is below where it needs to be, even considering the industry's issues at the moment, the benefits offered and the work/life balance. Secondary are the advancement opportunities, which tend to be nearly non-existent and very frustrating. In addition, once positions open up, they are available both externally and internally immediately, which, I believe, gives the wrong message to your employees who have been working long and hard for those opportunities. It would be better if the positions are only open internally, initially, and then opened up externally only if there are no good internal candidates. In addition, the company as a whole does a horrible job of informing its staff of openings, unless the employees are constantly scouring the job postings site.