1. No job security.
2. They give less selary than other companies
3. No fun events.
4. No HR person.
5. Poor management of resources. Any time they will kick you out of company.
If you have a skill and if you want to grow then there is a good opportunity.
Very supportive higher manangement.
Work flexibility.
You will get lot of things to learn.
Cons
As per my experience they needs some experienced technology specific person.
So project management will be easy.
Otherwise I don't think there is any cons.