Big Blue - great place to cut your teeth; leave before it makes you bitter.
Pros
Stable - fits the "just do my job" kind of person. Great access to self-study resources, if you find the time. I miss my ThinkPad. I miss Sametime. It's a great tool to connect with any subject matter expert in the organisation. And they're usually quite friendly.
Cons
Stable - don't rock the boat culture. IBM brags of innovation and all but the culture doesn't reflect it. Many good ideas never saw the light-of-day. Malaysia was (is??) seen as a low-cost and hence, unfairly, low-skilled location. Great developers never got the recognition they deserved and have since left. I myself have been passed over for a Bravo award just because of the numbers game. Some managers need to get past their obsession with the hierarchical organisation.