This is not the thing to test. DNS resolution time is important, but even if the google resolver returned results faster than your local ISP resolver it would still make your browsing in the general case slower. The problem is that the IPs for the resolvers have presence in very few locations around the world. I believe this number is just three at this time (Virginia, London, Taiwan). The big problem with this is the effect it has on CDNs and GSLBs. The DNS response you get for large sites, like www.bing.com for example, depends on the location of the machine asking the question. If you use your local ISP as your resolver then you'll get an answer that's close to you. If you use the google resolver you'll get an answer that's close to the google resolver and that will generate additional latency for all the rest of the browsing session. This obviously will affect all big sites that are NOT google. They're obviously aware of the problem since they have special cases for their own sites. If you have access to machines in different countries you can see the responses you get from 8.8.8.8 have good locality properties for google sites. So I'm guessing they're just forwarding the queries to their location-aware DNS servers. Obviously they won't do that for akamai, and others.

End result: you're farther away from the resolver, farther away from your web pages, farther away from your CDN. I don't see how you can make a case that this is an improvement in general.