Pros

Great offices with a great kitchen (snacks, drinks, breakfast)
Feeling of being plugged into an amazing communications network 24/7 (also a con)
Ask for more responsibility and you'll get it (be careful how much you ask for)
[Some] very intelligent and interesting work colleagues
Good at spotting and rewarding talent
Great focus on environmental issues, carbon footprint and recycling
Great benefits

Cons

Working hours
Work life balance
That 24/7 plugged-in feeling works both ways
[Some] not very intelligent and interesting work colleagues
Technology not cutting edge (unless you're very talented and able to push something new)
Lots of maintenance of existing systems
Types of work, job satisfaction and colleagues very dependant on which team you join

Advice to Senior Management

Senior management at the company is very entrenched, and not always open to new ideas. This isn't always a bad thing - stability in a large company is good, but sometimes it feels like a bit of a shake up at the top might be good.
Some managers definitely better than others.
Currently in the middle of a shift towards a new culture that is supposed to reward talent, focus back on growth, clean out some old crusty employees that are just coasting ("PLAN B"). Will be interesting to see how that works out over the next couple of years.