Very occasionally, not frequently at all, some websites are mis-categorized. DNSFilter has a process to get these re-categorized, and you can just whitelist, but the process can sometimes take days and days to hear anything back.
A year or so back, they changed their pricing structure and now is MUCH more expensive than it had been. We've stayed with them because they 'grandfathered' us into their previous pricing. If I was evaluating DNSFilter today based on pricing, I would have rejected them. I'm glad to their service, but I couldn't say that their pricing is competitive or not any more. It might be, I just haven't re-evaluated it. Review collected by and hosted on G2.com.