Pros
This place is awesome, with awesomely disruptive technology and an accompanying disruptive company culture. ;) The people are great, the work environment, for me, is great. I'm constantly being challenged... there's never a dull moment here which is great for me as I get easily get bored. The company benefits are the best I've seen anywhere and it's exciting to be riding a true technology wave -- leading the way and from where I sit (stand?) I see no end in sight. I can easily see myself retiring with this company which, in Silicon Valley, is saying something! :)
Cons
You gotta have the chops to work here. You have to be able to handle constant change and disruption. If you're looking for the easy 9-5 gig, this isn't it. The only real ding I'd give is sort of the nature of the beast with startups... You have to be *real* careful with the work-life balance thing. It's easier for me as my kids are grown, it would be a *lot* harder if they were still at home.