I too would have to disagree that it makes a site slower. I mean, one of their selling points is to improve a website's performance iirc, but they can't do much if their service hiccups for one reason or another. In the same way an Electricity Supplier offers uninterupted flow of electricity to whatever destination. However, in the event that some bozo drives over a cable with a forklift, there's not much they can do but get it running again asap. That doesn't mean they're not living up to their promise, since for all situations under their control, they uphold their end of the deal. CF in the same way can't do much if the servers they use go down due to say power outage, problems with hardware etc.
I do agree it can be annoying when stuff like that happens, but being hard on someone who has just as little control over these events as you or I is a tad harsh.