The best is being involved in one-of-a-kind type of work, sending spacecraft to space! The minus is budgetary concerns, and conservativism.
Pros: compensation, benefits, type of work
Cons: budget, conservativism
JPL offers you the unique opportunity to work on mission of deep space exploration. The tradition at JPL is impressive. You will feel proud of working there every day. And for that pride you will have to put up with a few things: conservativism, budgetary issues, aging personnel