Pros
(1) Awesome people - my manager was friendly and brilliant. My manager taught me a ton about business and understanding business data. My co-workers, with few exceptions, were extremely smart and helpful. How Wayfair got these awesome people is a bit of a mystery considering con number 1. (2) Great learning experience, especially for data analysis. If you're working in any of the analysis positions (marketing, data science, pricing, planning, business intelligence), you're going to learn a ton of SQL. That's a ridiculously useful skill across many industries, because just about every companies uses a relational database to store data. You'll also learn some Excel, which is often quite useful as well. Biggest pro for me: I landed my current gig because of what I learned at Wayfair.
Cons
(1) Low pay. As pretty much every review here says, the pay is awful. Don't expect it to increase anytime soon. That's because the company operates in online retail, which has notoriously bad margins especially in non-luxury categories. Since Wayfair is already bleeding cash from online ad spend (which anyone can see from the 10-K, now that the company is public), the company needs to keep costs down. Even if Wayfair eventually achieves household name recognition, their low margins aren't going to mean big increases in your paycheck (2) Ancient technology. Internal systems routinely break. When they're not broken, they're taking an eternity to load. This can make doing your job very difficult. The engineers work like mad to get things fixed, but there's only so much they can do when they have to deal with con # 3 (3) Turnover. Unsurprisingly, low pay across the board means people leave Wayfair quickly. (4) Limited ability to fix technical problems. Maybe this is true of all large corporations (which Wayfair has been for at least the last couple years), but your access rights are going to be restricted. So if you figure out Excel and SQL and need to do a little, say, Python to automate some aspect of your job, you won't be allowed to except for a handful of teams. Get used to lots of manual clicking and lots of frustration with your computer.