Pros
Tons of very smart and talented people. Plenty of opportunities to have a positive impact on the products, on how people use them, and on how teams function. Lots and lots of attention paid to little details around the office - food, events, and general atmosphere - which make it a generally pleasant work environment. Everyone is encouraged to speak their mind.
Cons
It's a company founded by and for developers, so if you aren't a developer then it's easy to feel left out. (I can't just stop doing my job for the fun hackathon; if I stop doing my job then things break, badly.) Many in the company also tend to forget that incremental improvement is sometimes a better option for change than doing all the things at once. There's so much to be done that it's disturbingly easy to overextend. Teams can be a bit scattered geographically, which makes collaboration difficult, and there's a very strong bias in favor of Sydney when it comes to promotions, thought leadership, and meeting scheduling. Everyone is encouraged to speak their mind, and many tend to do just that even when they have no idea what they're talking about.