Pros
The group owns a number of very cool and innovative companies, leaders in their industries. They have a lot of money and do not hesitate to spend it on you or trust you with it. It's also got a wonderful internal job market. They know it's really expensive to hire great people and they would rather see you move around within the group instead of leaving. With such a big array of companies and products to choose from, this becomes a really compelling thing to consider when joining.
Cons
Lots and lots of managers and bosses and directors and VPs and C suits. Things move slowly and some parts of the group can be very conservative. There's also a feeling that all these managers are part of a special caste, went to the same schools, go on vacation in the same places, live in the same areas… The higher, the more out of touch. If you're not one of them already or if you are not one of the lucky management trainees, your chances of climbing the ladder are pretty slim.