Pros
IBM is open and fair and pays well. I worked there for 9 years in Europe and they are extremely flexible to their employees, no managers breathe down your neck for petty things like vacation time, where you are working every day, free time, etc. They focus on where it matters - your job performance. Business goals are captured and measured twice a year in an online system. The collaboration between employees is exceptional because of the real-time collaboration tools. Most employees are able to manage their own time, work where and how they like, as long as of course they meet their business goals. The approach is fairly hands-off, which increases the self-imposed pressure to perform and meet your goals.
Cons
They are so big that sometimes you can get lost in the crowd. If you are like me you may want to move fast and find quick ways to close a complex global deal, for example, but you will have to work with many entrenched bureaucrats in their multiple fiefdoms to do anything in a non-standard creative way. Sometimes you have to deal with employees who realize that they can do the minimum effort, come to the office everyday, and basically rot away until they retire. Most of these fortunately are beginning to retire, but you still have some lifer-types who would need two months to work themselves out of a paper bag.
