Pros
It's a big company and has had a lot of success but there really isn't any competitor who has the size and profitability that CoStar does. However, I wouldn't really say the quality of CoStar's product is "good"by any means. The tenant info is EXTREMELY outdated, Showcase is a waste of money, and the Comps product has severe errors. I would only recommend this company to someone who is strongly interested in real estate and needs to get a start in the industry somewhere.
Cons
Management is horrible and incompetent. You will be micromanaged to the utmost degree, I worked at CoStar for several years and I witnessed managers hovering over employees shoulders as they did their work, require employees to turn in their cell phones in which employees could get them back at lunch and at the end of they day (As you can see, they think you're still in middle school), managers are very immature and gossip about employees and sometimes even start rumors about employees that are complete lies. Your manager is a glorified babysitter, they hate to offer help or guidance on projects and tasks, they sit at their desks and yell at you if you're caught on your phone or on any other website other than Enterprise (company software platform). Any time you need help or advice, you need to figure it out yourself. Office politics are at an all-time high, the hard workers don't get raises or promotions, the people who suck up to their managers the most do. I withnessed a guy with three kids get laid off once (and was a phenomenal researcher) but people who are BFF's with their managers and suck at the job get to stay. Management serves no purpose other than being puppets of the CEO and senior management. The company over the past year has set unattainable and unrealistic standards of their researchers, and those get more and more unreachable each quarter. They simply do not care about their employees- there used to be career paths and employee events to boost morale (company night at a Nats game, ice cream socials etc) and none of that exists anymore. You can find a much better job somewhere else, unless you want to work at CoStar and have the only good part of the day is when you leave at 5:00.