Pros
There is plenty to eat and be entertained by. Smart progressive colleagues. Easy commute in the city. Good work life balance. Cool products to work on.
Cons
During my 2 & 1/2 years at Twitter my team was reorg'd 5 times and was assigned a new manager on average every 3 or 4 months which made growth nearly impossible. However, after my second year and a lot of hard work I received a merit pay increase and promotion. The next quarter I was again reorg'd to a different team and given a 22% pay cut. My salary instantly became less than I was making before I joined the company. Shortly after discussing the financial hardships this was going to cause, reviewing my past accomplishments and performance reviews with the HRBP, my employment was terminated. Sidenote if you're a member of a minority group, run!