Pros
Competitive salary. EXCELLENT benefits package. Very accommodating hours (when appropriate). Many very skilled, intelligent and pleasant co-workers. Heavy emphasis on training and development; if you don't have a skill, but you wish to develop it, you can find resources at FactSet. If you are good at what you do you will succeed here.
Cons
As with any software company, we are often asked to fulfill certain tasks without being given the proper bandwidth and time to complete them at an acceptable level. For instance, while it's nice for developers to be able to take their computers home, the fact is that the laptops given to developers often strain at having developer environments for multiple languages, the compiled versions of our product, Outlook, and two instances of Excel open at once (this is not an unusual combination of programs that need to be open at a given time). Also, there is often a tendency to break away from the stated op plan and go chasing after relatively minor accomplishments. This doesn't strike me as happening much more than it would at another company, though.