Pros
Awesome coworkers. Intelligent, friendly, and supportive. Very flexible hours. No one keeps track of your hours, or how you are using them. As long as you get your work done you are in good shape. In general people seem to work their 40 hours and go home. Work/life balance is good.
Cons
IBM is very cheap. From the tools you need to do your job to the general work environment IBM cuts corners every where they can. The buildings are depressing. Many of the offices are small and shared. The sharing is especially annoying when there are empty offices all around. The furniture is from the 70s or 80s depending on the office. They recently stopped vacuuming offices because it cost too much. No free soda or snack perks. You can however get all the ice and water you want. IBM is also very much in the business of sending their jobs to India and China. I'm fairly convinced that they feel ok with not worrying about morale or work environment because it is beneficial for them if their employees quit or retire.