First ExperienceThe good thingsGood and pleasant team members. Highly motivated and supportive CEO that you cannot get it anywhere! The CEO always support their employees, give a lesson of what should do and don't, he always give best example by doing thing by himself. For example, look the project by himself and trust his employees.
The challengesThe challenging is when you have to do overtime and chase the project timeline. Sometimes you have to work more to gain more. Sometimes, in a month, you did not have a leave day when the project reached its peak. So you better be ready and it taught you a lot in the future in terms of experience and self preparation.