It actually DoSed a small VPS I had protected behind it. Not sure how, I guess it was scraping for content a bit too fast but my site ended up being more available without cloudflare on top of it

It randomly triggers and brings sites down. At least my experience with it on a few forums I frequent. All 3 of them switched after a month or so.

Hm. Will keep that in mind / watch for it, since I just started using it for a project. I have to say I was less than pleased when I added a site to my (paid) account and had to opt-out of having my error pages redirected to Cloudflare ones, but aside from that I haven't had a problem.