Pros
There can be interesting work and you can learn a lot if you work with the right people. The hours are more reasonable, in general, than management consulting or investment banking, but exit opportunities are not a match to either of those industries. You will have some very intelligent colleagues. There is a good PTO policy.
Cons
The promotion process to the 'professional' staff can seem completely inexplicable, with little to no practical advice given on how to reach that level. The skill levels of those promoted vary greatly, leaving the impression that nepotism plays a key role. You may find yourself in disbelief when considering the likely pay of some of your more senior colleagues. You are paid overtime, which can be amazing. You can also learn data analysis and programming, but usually SAS or STATA, which is likely not as desirable as say R or Python. There are no formal training programs of any kind. They do not comp education. The skills of its alumni thus vary greatly. The work is not innovative. Few people will take an interest in your career progress. You have to know who to work for to fully develop.