Avantages
If nothing else it beefs up your resume. They recently made a significant improvement to the employee personal computing website (the only SAPweb system was pretty bad). I've had very positive experiences at MIT medical, the hospital that services the health plan. The benefits are great - health, dental, eyeplan, T-pass.
Inconvénients
MIT oddly seems to struggle with handling issues related to computing -- its IT is a bit disorganized, it's unclear how to do simple things like finding servers to run computing jobs, accessing journals on JSTOR has to go through a ridiculous system called VERA that just adds more steps to be able to see papers, and until recently its website for the employee personal information/resources looked like it hadn't been updated in a decade. (It has since been improved with nice results.) These were all things that ran very smoothly at my last university.