Pros
Overall Cornell is a pretty good place to be a grad student, although of course your experience will heavily depend on your research group and your advisor. WIthin Engineering, most of the faculty are top notch and really know their stuff, and quite a few are literally the world leaders in their fields. Ithaca is a cool little funky town to be in for a few years, with lots of outdoorsy things to do and many good restaurants. The winter is pretty long and cold, but that helps you focus on your work. Also, go watch a hockey game while you're here.
Cons
Cornell's administration is known for "Big Red Tape." If you have an administrative problem it can take several trips to several different offices around campus to get things figured out. Also there is not much in terms of campus housing for grad students, so most live off campus.