I have no idea what is wrong, or how long they will take to fix it, but I'd imagine that CloudFlare has significantly better network engineers than the average company, and so they will fix it in far less time than the average company would fix the same problem.
But, for the amount of money many paid customers are paying them (in essence, anyone at that $3k/mo level that includes the critical 24/7 phone support), you can actually get an account with a company like CDNetworks or Akamai (if nothing else, with a reasonable CDN like EdgeCast) and have still-better network engineers than CloudFlare.
Also, even if you are using them for free: they aren't replacing people you have in house... they are an additional component that can independently fail, in addition to any of the things that would have caused your average company's network engineers to fail. They don't promise to cache enough content to replace much of your infrastructure.
“While we have not completed our investigation, we believe this incident was triggered by a product issue that Juniper identified last October, when a patch was also made available"
Good network engineers tend to apply newly release patches. This vulnerability was documented for almost half a year...
I have no idea what is wrong, or how long they will take to fix it, but I'd imagine that CloudFlare has significantly better network engineers than the average company, and so they will fix it in far less time than the average company would fix the same problem.