We haven't finished debugging yet. If you're using Pi-hole's DHCP server, you should make sure your router's DHCP is disabled. You should also restart your network devices so they pick up the new lease and DNS settings.
Several Google devices hardcode their own DNS servers, so that's a limitation Pi-hole has no control over.
I'm sorry you feel that way, but like I said, we haven't finished troubleshooting yet. Why don't you post some screenshots of your router's DHCP settings page and LAN settings page as a next step.
You can still use Pi-hole on devices that can have their DNS servers manually configured, but yes I understand your frustration on those devices that cannot.
We do link directly to our hardware/software requirements from the main page, but you're right, we don't mention anything about the router. I will fix that tonight.