Google's DNS service: Google public DNS

"A quick comparison of Google Public DNS with OpenDNS (which has been around for a long time).

If you have to access sites banned by Google DNS (or, OpenDNS for that matter), you can skip these configurations when you hit a problem. However, most of the time sites blocked by OpenDNS (and, I have to still look at Google Public DNS more) are those which I would never want to go to.

Update based on your comments on YouTube in other answers.
If YouTube is really banned by your ISP (or higher authorities), changing to another DNS will usually not help (unless this 'ban' is very weakly implemented). You would need to investigate tunneling techniques to bypass such bans."

Try using Namebench to see if it is faster for your location

"I tried it last night, but noticed it was slower than Level3 DNS, so I switched back this morning. I think it depends on your location. I'm in the east coast, so I think that's why I notice better performance with Level3.

I had the same experience when I tried OpenDNS, noticing Level3 was faster. Plus I didn't like some of the redirection OpenDNS does. I don't want my DNS thinking for me. :) Just fast."

I did speed comparisons 3 times during the day and night yesterday, and both my ISP's DNS, and Level3 came back as faster than Google DNS.

"I recently have to use 8.8.8.8 because I have AT&T as my Internet Service Provider.

When you try to navigate to sites like internal/ AT&T automatically redirects you to internal.attlocal.net

That is the way their default routing works.

To work around that I use 8.8.8.8 as my DNS server so that I can navigate successfully."