1. You get to work on broad range of technologies and latest technologies.
2. Open for (good) ideas.
3. Opportunities to connect to your client directly.
4. The founder himself is always ready to sit with you and discuss his business with you. This helps you to know how the business world exactly works.
5. Salary is credited on time.
6. And of course the Salary Hike, which is more than average hike paid in other organization.
Cons
1. No fancy amenities.
2. Being a startup, expect a lot of work (not a cons but this is not a leisure walk on a lawn)