Pros
I work with a collection of some of the smartest and hardest working people I've met anywhere (and I have degrees from some top institutions). The products present interesting challenges to work on while feeling like they have an actual impact on the world. Getting to interact with customers and patients is very fulfilling. I think the stock plan is fairly generous and the company has performed well on the market. The company pays for Caltrain passes, which is a nice perk. I do really believe in the ethics of my colleagues and management, from the individual contributors all the way up to (especially) the CEO. This is in contrast to some other companies I've seen around Silicon Valley.
Cons
This part of Sunnyvale isn't the greatest area to spend time - it would be nice to have a more dynamic external environment (but that is the case for most of Silicon Valley). The company could do more to facilitate commutes and encourage non-car transportation, especially as parking is challenging. Part of this is my role but I don't feel like there's too much room for me to move up (in part because I have so many talented colleagues).