Pros
In general, the company is well guided by the 50 year old mission written by founder Earl Bakken. The opportunities for learning and career development are there, although you have to work to find them and take advantage of them because the company is large. My best manager in my career to date was at Medtronic. There really are some smart people at this company, and people who leave consistently say that the caliber of people at Medtronic is higher than what you'll find at most companies.
Cons
For every fantastic manager I've had, I've also had a terrible one. Medtronic needs to better train management to lead: give specific feedback, give the coaching and resources employees need to succeed, set a vision and make sure all work falls within that vision. Lack of accountability has led to poor management and messy integrations. Facilities outside the Twin Cities lose the mission-based focus.