Great work environment
A great place to work that walks their talk. Great diversity initiatives. An exciting agile environment. Very flexible time off. Not as great in time flexibility--want you in the office 9-6, and working a skewed schedule (in late, out late) could be problematic. Also, people move around a lot on projects, and sometimes you've just developed a good working relationship when the team is re-assorted. Also, be aware that pairing may not be for everyone.
Free breakfast every day, great benefits
Company focus changes a lot, and jobs migrate to different offices