Google has announced that they are offering a free DNS service to anyone wanting to use it. Unfortunately the motivations/privacy concerns aren't being discussed in as much detail as I'd like, and people aren't asking the important question of why google is offering such a free service.

Several points to consider

Google can profile a given IP for which countries they visit, or which types of sites they prefer.

Google can identify sites you visit that lack google analytics/google ads, allowing google to know everything you connect to.

Google states they don't share the data with analytics or google ads, it doesn't seem to say it won't share this data with others.

Google may see queries to internal hostnames on your local corporate intranet/lan when you attempt to visit an internal site.

Google will be able to see the software products an IP uses, if those products perform web based updates.

Google will be able to tell if you're infected with malware, if that malware contacts hostnames for payload updates. This allows google to know if you're backdoored/infected which hypothetically means this information could be used to gather a list of hacked hosts. It also gives them the potential to control the payloads used by bots not using payload verification/signing. Am I saying google will do something with this information? Unlikely.

While it is true your ISP is in a similar position (although chances are they couldn't retain or analyze the traffic like google can due to lack of resources), your ISPs motivation of offering you DNS is to make the web work, while google's has some sort of yet to be determined financial benefit (they are a publicly traded company looking out for shareholders after all) which is likely related to your personal habits.

I believe google is doing the right thing regarding speeding up the web, however I have concerns that one day many people will regret handing over so much information to google. Hopefully once the original founders leave google entirely the do no evil message remains intact. The motivation for this post is that you should be aware how much information you give away to one particular company, while the service is 'free' you're paying a yet to be determined price.