You get a few benefits (protection against local interception) but it comes with a significant downside as it takes away the ability for an end user to identify if the connection is actually secure. For example I wouldn't enter my card details or other personal info on a HTTP site, but when CF is in front of it, I have no way of knowing if that's strict HTTPS to the origin or if most of the connection goes insecurely over the internet. The other problem is that CF makes it very easy for less technical website owners to click a button, see a green lock and assume everything is fine.