Pros
great people to learn from,nice work life balance,very vast business so there are immense opportunities to learn be it functional learning or business. For every skill or domain you want to start learning , there will be many good SMEs to learn from.Many career orientented presentations to benefit from and IBM has good focus for its resources to undergo certain trainings and certifications for betterment of both employess and company.
Cons
at times career path is not clear in absence of proper networking to get connect to right people as its a very vast organization.Pattern of promotion is more or less decided upon the kind of networking you have with in company.at times it is difficult to change your carrer aspiration and path because of lack of proper guidance and support.