Pros
I've gained substantial skills by working at Youstart. I got to work in a startup-like environment which is highly beneficial for carrer. I'm glad I got the opportunity to work on React Native which is currently trending tool to build apps. Working on React Native itself was a challenge as I was a beginner in ES6 and had no knowledge of React also. Secondly, React Native isn't well established yet but is still highly efficient. I also learned many nuances of building apps at a production level, Git version control, and managing deadlines. I feel elated by successfully building a music streaming app named Audrix with many functionalities. The working environment is so encouraging and all the mentors are highly experienced, humble and helpful in every way.
Cons
I, as an intern, did not face any difficulties.
But if you're looking for a job then you might have some cons which every startup have (like job security/stability, workload, earning and social life).