
The heavy emphasis on personal development and open, honest communication.
The opportunity to help out with other projects and teams. One isn't boxed in to a single position. They give one plenty of opportunities to develop or show off skills and discover what position makes you happiest.
The culture fit interview. I really like that they have this as part of the interview process. It helps build a cooperative team and helps one feel like they aren't completely adrift and new on their first day.