First, and most importantly, they suffered many hours of downtime to many sites hosted on their service, including their own web page, and still to this day have not tweeted or given any public statement about the incident. A lot of Googling got me some responses to customers who complained in private with weak justification about it being their upstream provider's problem and not theirs. The fact that they now estimate that it was 28GBit/s in traffic makes me even less trusting of their service, given that much larger DDOSes are flying around.
If anyone has any other services that are competitive, other than Cloudflare, I'd be interested in hearing about them out of curiosity. It seems there should be more than one company that can do this well.