Pros
People is amazing here. When I joined, everyone was so incredibly supportive, they made the on boarding easy and funny. You have tons of challenges where you need to be creative finding a solution, but most people are up to give you their insight or help if needed! Nothing is set on stone, so they're actually hearing you! Also: free lunches, if you want there's always something to do after work (also free beer... so you can start the party at the office!) and a nice salary!
Cons
Startup style is not for everyone. You are the owner of your work, so it's your duty to try new ideas, find a solution and push yourself to give the best. Some areas have no guidance: just you, internet and the problem you're facing. Some people don't like this pressure. People are relying on your work... so they'll be some times where you are going to stay a little bit longer. No one has pushed me, but you feel part of the company and, being honest, staying one more hour on the sofas with a couple of pints doesn't seem as overtime. But you're actually doing that.