Pros
The people on the whole, are great, smart people. The long-time employees here have lots of deep expertise you can learn from, and if you want to get into the tech industry, IBM has very good training programs for those who are just starting out, or just entering the tech industry. IBM is a great start if you'd like to learn what the corporate life is like, and how B2B deals and partnerships are made.
Cons
IBM is a huge company with many initiatives, sometimes contradictory to each other. This results in considerable internal fighting, and it takes a long time for initiatives to really trickle down and take hold. The company's internal processes are extremely backwards; the systems and software used to run the paperwork & backend have not changed for many many years. For any other company that may be fine, but this is an IT company that allegedly sells automation and digitize other companies. And as much as it tries to sell the story of "trying to get closer to start-ups" or innovate, not only is the company slow moving, it also very often fails to identify the true failure points of external and internal problems. I have seen time and again new tools, programs, and strategies trying to be rolled out, so much effort, investment, and have no one uses them properly because it fails to innovate the core pain points employees face.