Do the economics of their business work out? Or are they just gobbling market with investment money? For the little company I work for CF is dramatically less expensive than MaxCDN, which itself was dramatically cheaper than AWS Cloudfront.
And aside from that, I hate their attempts to differentiate via value-adds like this site scraper shield garbage, or their DDOS shield stuff. It doesn’t work well and isn’t trustworthy. I wish there was a CDN that just took an nginx config and got out of the way.