Pros
The experience of working across multiple customers. Ability to travel (when there is no corporate ban!). Lots of kit to get your hands on if you are in the right business area. Majority of people are sound. Working from home is encouraged. Flexible hours are encouraged. Big projects. Very big projects. you can always find someone to help if you know hwere to ask. HR is very important. Doing the right thing is encouraged. Worklife balance can be achieve if you are hard nosed about it. Decent tools to use. The really good people are promoted. You own your career no one else does.
Cons
Can be to big and to slow to move direction. When you eventually move direction, getting the rest of the business to move with you can be a hard job. To many processes. More time spent discussing an issue, costing more than the issue sometimes. Some strange business decsions are made without discussing even at a senior level the business case. Work life balance can suffer if you are weak. Rules are rules and once they are set you cant change them. Dont expect to change the world when you join. An expectation that senior management will carry you up the promo ladder is unfounded.