Pros
Redfin employs some of the smartest people I know, and they all care about doing their very best work. What's more, it's easy to enjoy working (and not working!) with them. The engineering is exciting and interesting, and with the combination of the great co-workers, it's easy to look forward to going to work. The perks are great, too - catered lunch a few days a week, generous time off, excellent insurance, and more fun than you can shake a stick at. Even better, you're really breaking new ground in an industry resistant to change, and individually having a big impact, which makes work really satisfying.
Cons
Redfin feels more corporate than it ought to - the internal values, and how they're encouraged, feels just like the encouragement of flair at Chotchkies. Unfortunately that undercurrent pervades many other parts of the culture, as well - not in many obvious ways, but as an influence. Not to say that the culture is entirely bad - Redfin has its heart in the right place, and on the personal level, the culture is as great as you could hope for.