Fantastic co-workers, lunch served M-Th, interesting product if you're on the right teams.
Cons
Specific to QA, they are moving away from any manual testing and to full automation as per the LinkedIn way (bought in May 2015). This can be seen as positive in some ways, but most of the QA folks are manual testers and will need to quickly ramp their skill sets to keep their jobs.
Great benefits, free food, flexible hours, decent load, great perks, good salary.
For developers, working here would be a dream job, as long as they don't mind being responsible for the testing as well (See below).
Cons
Testing is done by developers, which means as a QA your main job is to come up with scenarios and hand those to them. As a result, the priority is to hire more developers and (to put it nicely) employ less QAs. While this makes developers be more disciplined in designing with testing in mind, it also means less chances for QAs to learn and do new things.