Pros
You get free food twice a day. Many experienced people. In some departments the work is interesting. If you are ready to dedicate yourself 100% to your work this is a good place to be. If you want a balanced life, read below.
Kontras
Forget 9-5. Your rights are gradually taken away. You are made to expect long hours 'sometimes', then you are made to 'understand' that this is the norm. Company is no longer doing so well and future prospects are plain bad. Management is unusually mean and implies that you are never doing enough yet spends their time on social networks trying to get new jobs. The work is very difficult (for example, engineering work at Google is significantly easier) and if you put up with it at the expense of your life you are considered 'good' and more is given to you.