Pros
Seriously phenomenal marketing training... you will know more about strategy than the majority of your future colleagues. The brands are wonderful and diverse. Where else can you work on Dove and then go work on Ben & Jerry's or Olly's? The actual job depends 1000% on your manager and category.
Cons
The autonomy & love for the job will depend upon the category you are in and your leader. If you are on Dove, you will have a bigger marketing budget than anyone else, but you will have a team of 40 marketers and have to deal with a matrix of leaders around the globe that all play brand manager. A Sr Manager on Dove has very little autonomy, but your career is set with Dove on your resume. If you are on Breyers ice cream, you literally run the entire business as a Sr Manager as its a local business and your Director runs 6 ice cream brands.