Meta

Huge corporate upside potential (but might not apply to new hires as of 2012).

Fun work environment (free quality food, game rooms, frivolity encouraged, etc.).

High impact in terms of people using your code and recognition.

Good opportunities to try new ideas and move teams.

Brutally long hours for many, frequent pressure to delay or cancel vacation plans (even outside of release deadlines).

Harsh, unjust, and badly cross-team calibrated reviews, coupled with frequent firings, so that the stick is very close to the carrot.

It has now grown large enough that internal corporate politics have seeped in.

Management, at all levels, is fixated on lots of shiny new features, no matter how broken, and lacks respect for necessary work getting done.