Regardless of whether or not you provide your own SSL certificates, cloudflare still uses their own between their servers and client browsers. So any SSL encrypted traffic is unencrypted at their end before being re-encrypted with your certificate. How can such an entity be trusted?
Depends what you’re putting on there. If it’s some blog that’s out there for the world to see, and if you’d like to have more traffic checking it out, then privacy isn’t your goal. Now your personal data, yeah that’s different. I have that stuff segregated.
As I said in another comment, it’s more about your visitors than you.
Sure maybe if you have a completely generic blog about cooking or something it doesn’t matter much. But still as long as you can use that information (along with information from every other site that user visits through Cloudflare) to infer stuff about that person it becomes kinda scary.