Such a large, matrix style organisation can make it quite hard for new joiners to get to grips with, but once they do they realise it's a great company to work for with lots of opportunities. These opportunities can often be outside of an immediate business unit (due to flat structures in some) but they are there if you keep on top of the various communications, and network!
Flexible working is gradually being extended to all employees (i.e. not just those with children, for example) which is a good thing.
One of the best things about the company is the high quality products it produces. When directly faced with customers/customer feedback it's quite rewarding to see/hear.
However, my colleagues have been the best thing for me over the years! A great bunch of very dedicated, hard working, but very fun people.