Pros
As a small company, everyone can speak with everyone in informal manner. People are helpful, supportive, give you tips and constructive feedback about your work.
You can give your ideas and participate in brainstorming, you can work in your own project.
It's a great place to become autonomous and unravel your work on the go.
There is great work culture, they accept your inputs, they have some teambuilding events as outdoor activities and some company meals.
It's cutting edge software that might turn the world, they have a great mission.
Also they have seminars where you can learn about parts of your teammates work.
Cons
You have all the cons of working in a small startup company.