Pros
There are some very smart people here, and some very interesting technology. Lots of fun techie toys to play with in the course of your job, and a decent amount of support (sometimes) for doing things in new and better ways. The pay is decent, if you can avoid getting screwed over by the recruiter when you first start. Work life balance is typically respected, and it's extremely easy to get time off or work flex time when you need to. The locale is good, with lots of things to do when you aren't working. Plus you get to make Balmer Chair jokes.
Cons
The review and promotion system is pretty obviously designed to pit employees against each other. Like grading on a curve, which makes no sense if you want to hire a bunch of really smart people and keep them all motivated and happy. Management is fumbling and confused, and seemingly care more about making one or two feel-good changes they can put their name on and leverage into a better position elsewhere than actually improving products or the business. Oftentimes lip service is paid to "Engineering Excellence", and then scrapped immediately when Bizdev remembers something they should have told you months earlier. Good work goes unnoticed unless it's on some shiny, highly visible area; which is fine, except that it creates an environment where the basics aren't attended to because they're a career dead end and nobody wants to take that hit. Finally, hiring standards have lowered drastically in the past several years, so there are a lot of people who really shouldn't be working there but are now impossible to get rid of. At least they help pad out the lower end of the review scale.