I love this place because it has given me so many opportunities to try hard new things and grow but I've also had some of my most stressful life events while working here. Being lean and scrappy also means that when the shit hits the fan you are often times looking around for the "expert" and realize that you are supposed to be that person and if you don't solve the problem then everyone is fucked.
To give a little more context. The Site Integrity team fights spam, abuse and protects people from having their account taken over and when I joined over 5 years ago there really weren't too many people thinking about this stuff every day. I had previous experience with some of it from working on orkut.com so when I got here that is the kind of stuff I was able to have a lot of impact on. Spammers are smart and try to hit us when we are asleep or on vacation and I learned that the hard way during a trip to lake tahoe shortly after I started where I literally fought a spam attack for 2 days straight while my friends and family were skiing. I'm not complaining though because I found out that I am able to be very clear in situations like that every attack made my game that much better. Most everyone on my team is just like that but there are a number of people that really need a lot of backup and need a 9-5 routine.
FB is attracting more and more people I know who are top notch technically - Alex Feinberg, Simon Marlow, to name a couple. With Google the impression is that the really cutting edge people are the 'old guard'- Ghemawat,Dean, Norvig, Horzle (spelling?), even Guido Van Rossum.
Here is one more FB edge: From a purely local (Indian) viewpoint, FaceBook hires ultra sharp people for its US offices, vs Google mainly hiring into the local (Bangalore) office, which is a horror politically (i.e manager competence and behavior) and technically, and then (by HR policy) making you wait 2 or 3 years before you can transfer. I really wish someone at Google HQ would do some Augean stable cleaning here.
As of today, for a sharp Indian dev, it probably makes more sense to apply to Facebook than Google.
But then OTOH Larry and Sergei are more inspiring leaders than Zuckerberg. So ...
(due disclosure: spoken as someone who has no intention of working for either company, and has no axe to grind for either company. just stream of consciousness, and it is the middle of the night here, so apologies for any incoherence)