Pros
Generally speaking IBM offers an interesting, challenging and expansive work environment with good career opportunities. If you deliver your quality work on time and are a good team player, then you'll get rewarded. There's equal opportunity. There's lots of chances to further your knowledge through a vast offering of education opportunities. IBM rewards people who take charge and shows interest in the business.
Cons
Mediocre salaries and declining benefits. Poor long term employment stability prospects. Generally old and uninspiring work environments. Mediocre cafeterias. Work weeks of 40 hours is not so. It's easily 50+ hours in any of the full time development jobs. People are frequently, though politely, asked to do whatever's needed to get the job done.