Most of the time the fastest way to any given site is to avoid unnecessary network hops.
Now maybe CF have a more efficient route here or there but really I can’t believe that for most people it’ll be faster.
As for security or privacy I can’t imagine they’re much safer than browsing most HTTPS sites directly. There’s nothing to say they’ll be able to resist a secret US government subpoena for records either.
You'd be surprised at the poor path that the average packet takes. Cloudflare has lots of PoPs that are very close to major cities so it is very conceivable that if that brings you to a higher quality backbone it would result in better performance overall. I don't know about the quality of Cloudflare's backbone but at Google you could definitely get noticeably better performance by quickly getting into the Google backbone and popping back onto the internet near your destination.
Yes, they maintain prioritized links between their datacenters, many of which are fully private. However, the Warp free plan simply bounces to the nearest CF datacenter which participates in Warp (not all of their centers do) and then back into the public internet, though it's through their massive pipe. Warp+ uses their Argo routing through their private backbone to get you as close to the origin as possible within the Warp network.
The only real advantage I see is that it could be useful in coffee shops and hiding your connections from your computer->isp->cloudflare. isp can't see your traffic and headers other than that the encrypted pipe has been created between you and cloudflare "vpn"
Now maybe CF have a more efficient route here or there but really I can’t believe that for most people it’ll be faster.
As for security or privacy I can’t imagine they’re much safer than browsing most HTTPS sites directly. There’s nothing to say they’ll be able to resist a secret US government subpoena for records either.