Pros
It is a reputed company, and nice to have this brand name on your resume. Salary is competitive if you have other offer. Benefit package is reasonable.
Cons
The work/life balance at IBM is horrible. They want to suck all of your time and energy. IBM literally wants your 24/7 devotion (except during your 15 days vacation time). The immediate management always assign tons of work and says you have the flexibility to work from home (which they know it is impossible to finish at office). They always fire lots of people and hire fresh graduates. If you argue little bit with the management you will be on their red list and when the work-force balance time comes (which is nowadays almost every year) you will definitely get fired. Salary increment is very poor and you always have to chase the time line. IBM always believe once the employee accepts the job offer, they buy the candidate. IBM is a golden cage where you have no freedom.