Pros
1. learning experience 2. variety of exposure to different projects. 3. If you are aligned to the IBM way of life, you can have a great time. This also means that dissidence/alternative view points are not liked.
Cons
1. IBM and IBMers tend to be extremely arrogant. 2. For those who look to do cutting edge work or look for the chance to create IP, IBM is definitely not the place. GBS is focused on meeting customer needs and ISL tends to be more of a testing organization where products are moved to India for maintenance & support. 3. Salary is 25-50% less than industry. 4. Given its size, IBM is only concerned with numbers - eg. people are resources and not much more. 5. To get their job done, IBM managers will attempt to browbeat you or manipulate you, thus leaving a dirty taste in the mouth.