Pros
Their job descriptions are great. If you like to have your job description to say amazing things, this is the place for you (unless you're actually interested in the content of the actual role)
Cons
Dinosaur culture. Almost everyone you will meet working at IBM started their careers at IBM and there is a reason for that. The employees or senior management don't really have exposure to the real world and they just don't know how bad the place is. Things like the lack of coffee or proper drinking water for employees do not bother these people because they haven't seen any better. The place is a dump. Culture is awful and from the actual work you do (which most of the times is completely meaningless, because of the antiquated management and reporting systems in place) to the treatment you get at the cafeteria (where you are a paid customer but the guy at the grill is out smoking while the cafeteria is open and the cash register person is nowhere to be found because you're in the middle of some kind of forest and there is nowhere else to go) everything is awful.. but because nobody at the company has seen any better, nothing ever changes. If you come here with prior work experience, nobody will care about or even understand what you did before. Management isn't interested in the real world outside, and the results they produce show it.