Pros
It really depends on personality type - it is a highly structured organisation and if you crave structure then it is the organisation for you. It is great for someone at the start of a career with little or no idea of where they want to go, IBM will have a home for you , you will get training.
Cons
If you want automony and dislike structured bureacracy then avoid this company. IBM seeks to treat all employees the same regardless of career path, experience or work. In an organisation as diverse as IBM , it fails to recongise the diversity of its people, manufacturing, sales, consultants, call centre agents , the list goes on and on. How likely is it that the management of call centre agents is suitable for running a manufacturing line or a consultancy arm for that matter?