tl;dr: don't expect to be paid what you could easily get elsewhere.
All of this is from the perspective of the engineering department:
The pay is laughably low compared to companies looking for similar talent. Turnover is a serious problem. Employees and lower management have brought this to upper management attention, but they have responded with "that's not going to change." This has been going on for years, and management occasionally applies band aides to keep people from leaving in droves.
Here's why:
The personnel strategy is to hire tons of bright kids fresh out of college for pennies, with a bare minimum of experienced folks to corral them. They sell them on the "startup experience", which Wayfair decidedly is not, and has not been for many many years. Recruiting even goes so far to up sell the "stock options", which amount to a couple grand vested over 5 years. That's right. It's about $500 per year (if that), and the recruiters make it out to be like investing in Apple in the 70's. After about two years under their belts, these kids start hearing about the career growth of their friends, and especially the pay raises. The best ones leave, and experience a 50-100% raise in their salaries. I'm not exaggerating about that. I wish I was. I have had several friends who interviewed elsewhere in order to get Wayfair to propose at least a competitive counter offer. Wayfair refused, and so they left, despite not really wanting to leave. I received a similar increase when I left.
For those experienced folks, there isn't much movement in the career chain, so there really isn't anywhere to go. Most of the management is made up of folks that have been there since when Wayfair really WAS a startup. Most of the early employees who would have moved on to another opportunity have already done so, and the ones that remain have no plans to leave. The only way for the technically brilliant folks (who do exist there) to get the pay they would see elsewhere is to go into management, where they usually perform poorly. There is no viable "technical career path" like other companies.
Don't be fooled by the rationalization that Boston is an expensive city to live in. It is, but you will get much better pay at other companies in Boston. Think about that when you want to rent a halfway decent apartment or maybe own a house someday.
