Pros
Great balance of start-up culture with enterprise technology and support! You never see anyone in a suit, there are free snacks / refreshments, great work life balance, awesome after-hours events. Specifically for Engineers: rather than mandating the use of existing technology and processes, teams are instead encouraged to experiment with the new, assimilate what is found to work well, and share their newfound knowledge with others. Also, I've been glad to find more gender-diverse engineering teams than I've seen at other companies.
Cons
If you're looking for your manager to tell you what to do every day and give you a big raise for doing only that, then this probably isn't the place for you. As with any office, there are examples of political decision-making, etc. but I've found these to be the exception rather than the norm.