Pros
Wayfair is overall a terrific place to work. The people are friendly, fun and exceptionally smart--the kinds of people you want to be friends with. Life is balanced, though you sometime have to set your own boundaries, with lots of working parents. People are given tons of ownership over their work and the high growth means no shortage of opportunities for advancement and lateral movement around the company. Benefits are quite good given that ecommerce is a low-margin business (you should compare to Amazon not Facebook/Google), and high equity compensation creates really big upside for people who stick with the company over time (though better paternity leave is much needed!).
Cons
As many others have noted, the high growth creates some tension. To excel at Wayfair, you need to be flexible and willing to work in constantly changing and often ambiguous situations. The management really does care, but occasionally makes mistakes--not fully understanding the concerns of the employees or not appropriately supporting someone who is new reporting to a new manager who is reporting to a new manager. They are actively trying to improve on all these fronts while still growing 40-50% a year. They mean well, but it's easy for a companies core cultural values to get fuzzy in that situation. If that sounds scary, then Wayfair probably isn't the right place for you. Also, the organization actually isn't very corporate and there isn't a lot of red tape--I often wish there was more. There are plenty of times when something would be may more efficient if it was standardized, but Wayfair expects you to make it up as you go. It's a constant evolution. We are definitely BIG... having so many people means it's harder to get information you need or coordinate across departments than it may have been before. But folks who have worked at much larger organizations will recognize these as the normal growing pains of a fast-scaling company.