Pros
Brand and company are great to have on your resume, everyone knows big blue.
Cons
Innovation in the company is less and less the focus is shifting more and more to cater to wall street. The days of ibm being a company of thinkers and great innovators is long gone. For employees especially American based, every day is lived in fear that today will be your last. Raises and bonuses even for top performers are below standards if even given at all. Negotiate up front only newer employees from outside have remotely competitive base salaries, once in be prepared to live with that salary regardless of duties position or band prerequisites. If cost of living and above average performance combined is worth 1 or 2% a year then this is the place for you.