Pros
If you enjoy working with kids then it is a nice job that you can do from home. It also pays fairly well (depending on what area of the country you live in). By far one of the best things about the job is that you can set your own schedule. VIPKID has a lot of nice free resources available for their teachers (workshops, written material, teaching material and other teachers to review your teaching and to help you). VIPKID will frequently listen to their teachers and make improvements in the curriculum and their website.
Cons
It can be kind of hard to get bookings to begin with especially if you are not able to open up the peak time slots. The early morning hours can be tough. Sometimes once you are a more established teacher your schedule may be lighter during the Chinese holidays. After one year you may be eligible for a pay raise but it is not easy to get. Then, you need to wait another year to be eligible again for a pay raise. For the average teacher it is hard to get career advancements as many other teachers are all applying for the same positions.