Pros
I didn't have to work many weekends or late nights. Free fruit and healthy snacks. Good gym and showers. Stable company with monopoly business model, so you don't have to worry about the company going under.
Cons
The place is run like a frat house. If the CEO (Andy Florance) doesn't like you enough to put you in his "inner circle" then your days are numbered. I saw a lot of capable, experienced people fired with no notice and no cause simply because the winds shifted or something minor happened. Or their boss needed a scapegoat to slaughter to appease tyrant Andy. People management is mercurial and unprofessional. Very little diversity at the top, especially when it comes to opinions. There's only one brain allowed at CoStar, so even small projects stand still until Andy gives the go-ahead (long time survivors know not to make a single, small move without his express approval, and even then you risk a bad mood nearly cutting your head off). Don't expect any professional development here. None of the senior leaders are very well developed themselves, especially since they've spent their careers in the dysfunctional orbit of CoStar. Experience outside of commercial real estate is dismissed and unvalued. The industry is "traditional" and incestuous - not a great place for people of color or women. Turnover is huge and margins are low. Worker discontent is epic. They use free stuff and perks to make themselves feel like they're good employers. Much of the work feels silly, outdated, or circular, and there's an immense amount of waiting to hurry up and hurrying up to wait. Andy speaks and everyone jumps, until they're not in the spotlight, at which time they dawdle and wait for guidance from the king. It's no accident that CoStar was rated the worst employer and the worst CEO in DC - it's true. After working here, don't be surprised if you end up with a case of post-traumatic stress disorder. The "reality" at CoStar is upside down vs. the reality of other [well-run, professionally managed] companies, and working here too long will make you doubt yourself or learn terrible habits that wouldn't fly at other companies.