Inexperienced management with big egos, and lots of politics. For the most part, management is hired from outside, and those who get promoted into management positions are very good at navigating the copious amounts of politics in the office. The ability to manage people doesn't seem to be a criteria in promotions or hiring decisions.
No conferences - Wayfair will not pay for engineers that are below Level 4 to attend any conferences, even if they take place in the building next door, in Boston, and cost $20. This is the company's official policy, and the fact that a conference is highly relevant to your work is perfectly irrelevant to management. If you want to go to a conference, be prepared to pay for it out of pocket, and clear the PTO needed with your manager well in advance.
Poor working conditions - the office is very cramped, and every employee gets exactly the space that their desk and chair take up. Nothing more, nothing less. If you need quiet time to focus on your work, plan to do that at home, because if you are lucky enough not to sit next to a sales team or some other group that is on the phone all day, you will definitely be distracted constantly by the high foot traffic in the office and loud chatter everywhere. Most people wear headphones, but it is impossible to block out the noise of 1,000 people on a floor with no walls or dividers.
Virtually no flexibility - time off is hard to come by at Wayfair. If you are lower than level 4, you get a small number of paid days off that include both vacation and sick time. If you happen to have planned your vacation but inconveniently get sick before or after, good luck. If they are out of PTO for the year, most people tough it out and come to work sick, but if you still have PTO, you can take it and stay home - though you might still be expected to work, unless you planned to be sick and have somehow managed to wrap up all your projects before your sick day. Being too sick to leave your place is also virtually the only time when working from home is begrudgingly allowed at Wayfair, even if you're one of the lucky few to have a laptop.
Widely implemented buy-your-own policy - When you work at Wayfair, you get the absolute bare minimum you need to do your job. You get a desk, a chair, two standard Dell monitors, a Dell tower, a standard keyboard and a standard mouse.
Want a bigger monitor? You can buy one yourself.
Want a laptop? Most people use their personal ones when they need to log in and work some more after hours.
Want a wireless mouse so your cord doesn't get in the way all the time? You can buy one yourself. The only office supplies in the office are limited to blue and red PaperMate pens, and yellow legal pads. If you're lucky, you might find a stapler by a printer when you need one, but that is not a guarantee. Again, most people bring their staplers from home if they need to use them.
Low pay - It is well known that Wayfair pays very little compared to the other companies on the Boston tech scene, and they get away with it mainly because they hire people straight out of college who are too scared that they won't get another offer and accept Wayfair's lowball with no pushback. They have recently started increasing offers for experienced engineers and some other functions in order to attract more experienced talent, but you will typically have to negotiate in order to get a competitive offer from them.