However, They're telling end-users to "try" their DNS service and giving basic instructions.
Their geo-location is no-where near complete, for end-users in (for example) New Zealand who follow their instructions they'll have:
* Pro: A DNS Server that will most likely have nearly all results cached, quicker overall response.
* Pro: DNS Infrastructure redundency through Google.
* Con: A DNS System with higher latency.
* Con: A DNS System where if using only those two servers (through Googles instructions) when International connectivity dies, so does all your DNS.
I've moved my home server over to 220.127.116.11, 18.104.22.168, ISPDNS1, ISPDNS2 to negate these issues and provide better DNS service than my ISP.
I honestly would have expected more from Google, at the very least a geo-location test to ensure they have DNS servers in your "region" before advising to "Try" their system.