Pros
Great place to learn with ample resources to do your job with and explore interests. I found that subject matter experts were generally easy to get in touch with and learn from if proactive about reaching out. There's always something exciting happening somewhere in the company, and offering management has great exposure to much of what goes on. Found IBM's corporate values were generally prevalent across the company. Met many people who became sincere friends outside work.
Cons
Matrixed company felt disjointed and difficult to move around; it seemed like two people could have the same job title and be doing very different things, or be in different parts of the company and have very different experiences. A lot of bureaucracy at times, and the work could be a grind. If you love engineering and dev/ops, you'll probably be happier here than if you love B2C work. When IBM gets it right, they really get it right, but you have to know up front that IBM isn't the right place for everyone.
