Pros
IBM is probably the best company on earth that has successfully incorporated work/life balance into its business culture. IBM helps the world get a little bit more green by supporting its employees flexible workplace options and thus help reduce consumption of fossil fuels for commuting. IBM for the most part exhibits tolerance towards diversity and different backgrounds and truly incorporates diversity into its business model.
Cons
There is very little career prospects or skills growth opportunities once you join at IBM at any given level. New projects and job opportunities are handed to known and safer contacts within the department and there is very little if any cross-departmental hiring (huge silo mentality). It is near impossible to get promoted and very difficult to get reasonable salary increases even if you put in years of your life with hard work and dedication for client success. Constant threat of off-shoring and reorganizing people at the whims and fancies of executives and low-morale of the employees.