Vantaggi
The company is huge, so there are many interesting jobs, and you meet and often work with people from all over the world. They also tend to be pretty good at seeing upcoming trends and reacting to them. You also still find that you often work with some really outstanding people.
Svantaggi
The concept of "Respect for the Individual", which guided the company for decades, has gone out the window. An example is the changes to the retirement plan. Pension was replaced by a 401K match years ago, which was actually good if you planned to stay a few years then move on. But then instead of matching each pay period, they now make the payment at year end, so IBM gets the interest on the match, not you. And if you leave, are laid off, or divested before December, IBM gives you nothing at all for that year. Morale is also pretty low in the "old" businesses as the company continues to aggressively cut costs in its traditional business units.