Ventajas
You'll grow up there in any way technically as well as mentally. The company allows you to be agile in your decisions, which tech stack to utilize, how to deliver etc. Be prepared to run as fast as you can, and afterward, start doing it twice faster. If you prefer a smooth and easygoing pace of working this is definitely not a place where you find it.
Desventajas
Like in any other startup, the working environment overall is quite dynamic with the rapid changes to product requirements, lack of processes, tight deadlines, some overtimes (not frequently), and other charms inherent in it.