Personally I dislike CloudFlare for the simple reason that they encourage site owners to use their lossless image optimisation service, which isn't lossless. Thus many images appear different than intended when hosted behind CloudFlare. I wrote about this earlier: https://news.ycombinator.com/item?id=10192587

Quote from their website.

The Lossless mode removes all the unnecessary bloat from an image file, such as the image header and meta data, without removing any image data. This means images will appear exactly the same as they would have before.

The last sentence is false, at least for images with color profiles on all non-mobile browsers. There are other possible minor cases.