Pros
-Fun work environment and beautiful office. I had a blast during my time at Wayfair. You'll make lifelong friends. So many smart people. -Fast company growth can open doors and give you experiences that you wouldn't have received at a slower company - especially if you're an entry-level employee. While you won't always get a promotion or a pay increase to go with it, it will make you more valuable to other employers.
Cons
-Your experience as an employee can vary drastically depending on your department, team, and manager (which will likely change within your first year). -Lots of new people who don't always know what they're doing. In my opinion, this company grew too quickly. -Compensation is pretty far below market rate in Boston for just about every department. Too many people take a pay cut when hired into Wayfair. -Work/life balance can be pretty terrible, but again, it depends on your department. Too many people burn out and end up having to leave, and it's tough to watch. -Diversity is an issue. As others have said, there is an increasingly elitist feel to the company, with many ivy league and consulting alumni at the company. Wayfair is large enough now that hiring, developing, and promoting people with many different backgrounds needs to be a priority.