Pros
1. Because of its reputation and standing, it gets interesting assignments and you get to do interesting work. 2. It has a large, organized reservoir of templates, models, tools and instruments -- and training to back their use -- and you can learn and grow in your profession. 3. It has many competent professionals and encourages 'communities of practice,' which aids professional growth. 4. IBM is huge and involved in many different lines of exploration, which in turn broadens your professional view and, if you choose, helps you develop your knowledge and skill in a new or different direction -- a major career advantage in a time of radical flux.
Cons
1. Despite its claim, it is a very mechanistic organization, which has an engineering approach to its employees, who are viewed as cogs in a machine and left to feel used and dispensable. 2. Despite an elaborate on-boarding program, its treatment of new employees is casual and thoughtless, and the initial period for newcomers is hard. 3. It is particularly bad for younger employees, who haven't had long working experience and are not principally self-directed; they often rudderless and lost in a giant maze. 4. Most employees are now 'virtual' and get scant team or organizational support, leaving them isolated, unsupported and painfully on their own.