Startup is a place where you will you work with team which is self motivated. You need to be pickup pace and match it with company from very first day. You will learn things quickly.
I learned how to communicate professionally with internal team as well as externals.
Environment is quite aggressive but that is how startup company work. If you wants to learn agile development you need to be in environment like this.
Cons
1. Working with long period there are so many ups and downs. But one thing that is strict office timing that will effect on work/life Balance
I was with Turaco Mobile for 2.5 years and it was a wonderful experience. As a fresher software engineer, I initially struggled a lot and my leads helped me for months. I was given an opportunity to move from back end work to front end where I worked hard with constant guidance from my leads and did very well over time. I learned much and here I excelled in Angular and that eventually gave me a wonderful career opportunity. The management always supported and had good clarity on requirements and work.
Cons
No cons at all. All depends on you how you look at any situation.