Pros
The people and the atmosphere. When I was first recruiting, I even got skeptical because I could not believe that everyone at this company is so passionate about the work they do - when they talked about it, their eyes glowed and they just couldn't stop. But when I joined I realized it is true, and it doesn't just apply to my function (Marketing) - I've had the opportunity to work with cross-functional teams where people are so passionate that I have my R&D colleague approaching me about an opportunity to improve margins and my Finance colleague about an idea for a new product. It truly make working here a very enjoyable and easy experience. All this is enhanced by the fact that we work in a gorgeous campus - it's the best I've see (and I've seen many, since I used to be a consultant). We even have an art curator to take care of all the art around the building, the cafeteria is amazing, we have a great gym, hair salon, concierge, company store... what else could you want?
Cons
The only downside right now is that the company is doing so great in these times, that no one wants to leave the company, so it's creating a backlog and it's taking a bit longer than usual for people to get promoted. And because General Mills pays so much attention in hiring very bright and passionate people, and because it's a very caring employer, they are not very active in managing people out.