Pros
Working with talented, intelligent, driven, and extremely helpful people. Startup tech life at its finest: beer, whiskey, ping pong, dart gun wars, free lunch that taste great, useful/purposeful technology, thoughtful approach to solving real problems, not having to work long hours like most startups, fun & frequent company outings, and an open environment. CEO is easy to approach, will listen to anyone's comments, and is personable. Pay and benefits are hard to beat.
Cons
Ive been here for almost a half year and have been searching for something to dislike/improve. I felt at some point the "honeymoon period" would wear off. It still hasn't... The one thing that is sometimes hard to deal with but is consistent across any rapidly growing company is things are constantly changing, usually for the better. If you can't deal with change this isn't the place for you.