Especially when you read their privacy policy, realize they're a Chinese company, and see this: "However, be aware of the possibility of surveillance by intelligence agencies in your home country and our home country."
I wish this was higher up in the discussion. This is a very interesting point, not only when considering the Puffin browser, but considering this entire company. Their whole business model is to improve traditionally-local software by having data processed in the cloud. I have seen people affiliated with the company reply to other comments on this post but yours demands some sort of clarification. This company's real business is selling reports generated from the logs of its users' activity.
Puffin is not a Chinese company.
They are based in Taiwan based on their job postings [0]. Whether or not Taiwan is technically part of China is up for debate, but the two are defintiely linked.