Vantaggi
Interesting technical challenges with a ton of opportunities to really pull things apart to see how they work and design new solutions.
Wide variety of projects that still add value. Feel like doing some micro optimizations? No problem; you can do so without feeling like you are spending your time sub optimally. Another day you might want to hack on some web ui - still helpful. Or run an experiment with billions of records, or dive deep into the TCP stack.
If you've ever been interested in "big data" or using Hadoop, you will get your fill. You can use Hadoop if you want, but they have their own platform which they actively develop and works more efficiently if less smoothly.
Working here will teach you so much about data processing and analysis that you will not only look down on people who use Hadoop/MapReduce, but on the very developers who made them.
Engineering management is competent and reasonable. Work hours are extremely flexible. Coworkers are all pleasant. Free lunch, snacks, drinks etc.
Svantaggi
Most of the company won't understand what you do. Neither will most of the internet.
The flip side of having so many things to work on is that the age old "20% of the work for 80% of the benefit" frequently compels you to let ever more perfectly reasonable improvements/ projects sit in your back log.
Other parts of the company are sometimes a little more volatile