Pros
There are lots of global opportunities for those who want to travel or live overseas. The pay is good. The benefits are standard. Because IBM is such a huge company, there are lots of diverse opportunities -- anything from storage technologies to point-of-sale systems, hardware, software, some cutting-edge stuff and some not so cutting-edge. IBM does provide a lot of online resources but they are not easy to find--you have to be resourceful. It's great that the company is focusing so much on telecommuting -- it's really becoming more the norm. You can work from home, have an office or both (sometimes you have a choice but not always).
Kontras
If you have a good manager, it makes all the difference. A bad manager, and your life can be miserable. employee morale is usually low, at least in my area, because we don't feel our jobs are secure (due to globalization and layoffs) and people feel pressure to work overtime. Sometimes it seems that IBM consists of a bunch of little fiefdoms with little communication between them. Also, some way-up corporate layer makes "money-saving" decisions that often winds up lumping way too many projects under a first or second line manager, giving them little room to devote necessary resources or energy.