From what I have tested, it finds IPs quickly, exactly what it should do. However, one big problem. It resolves to the actual IP of a domain instead of resolving to the closest CDN. For some people that might be great, to me, that's an issue on websites such as YouTube where videos take longer to load. I'm not sure I am using the right term but here is an example.
nslookup google.com with my current resolver: IP 216.******** (which is a server in Los Angeles, closest to me, ping 23 ms)
nslookup google.com with Cloudfare: IP 74.******** (it gave me the result instantly, but ping is 187 ms)
So whatever is going on on my end, Cloudfare gives me fast results but points me at the wrong servers.