Pros
Opportunities for people 0-5 years out of school are awesome. There aren't many places you're going to get to do A/B testing in front of millions of people when you're straight out of school. Management sticks up for employees repeatedly... for example, health insurance rates skyrocketed with Obamacare and they're still covering 100% of premiums. The CEO genuinely means well and is a good guy. Over the years, a few employees have had life catastrophes and the company has been very supportive. It's a relatively small team with a flat structure and a casual environment, no politics. It's a typical internet company; most people listen to their headphones, and many wear flip flops. Work hours are comfortable too... not some bay area flex thing where you can come in at 3pm every day, but no one is dishing out reprimands for coming in at 9:03. Most of the team genuinely wants to continue improving. A couple years back, nearly everything was dilapidated legacy tech, but it's seen a lot of automation & upgrades since then. Ask the techies. The flagship product is ads on reference sites that get a ton of traffic. The ads sell well with many years of renewals for many clients, including some in the Fortune 500. 60%+ is from US, Canada, Europe & Australia. You can verify this yourself on Quantcast or DFP. Google tested 41 shades of blue for a button. We're not that wild, but we're definitely data driven and very transparent. Revenues and performance stats are readily available to all employees. Overall, it's a great company to work for, and employee retention is generally 2-5 years.
Cons
No 401(k) or ESOP. Social life is so-so. Tech meetups & lunch with the team are fun. The office is in Fairfax and a couple miles from the Vienna metro, so you practically have to drive. You can take the metro+bus in a pinch, but you won't want to. Happy hour after work tends to be tame because no one wants to pound 4 brews and then hop behind the wheel (understandably). This next point is a mixed pro/con depending on your own goals. The company's main product is advertising, and it's still a consumer web internet company at heart. If you like either, this could be a great match for you. If you want to build a career in other fields that are really popular in the DC area (e.g. healthcare, consulting, law, or non-profits), this probably isn't a match for you.