I have fixed feelings. I have tried it both ways and still not sure if it even matters.

Some say a service like Open DNS or Google Public DNS can improve lockup speed and HELP PREVENT attacks for hostile web sites.
Here is a short bit:

Before you change your DNS settings to use Google Public DNS, be sure to write down the current server addresses or settings on a piece of paper
...
The Google Public DNS IP addresses (IPv4) are as follows:

8.8.8.8
8.8.4.4

https://developers.google.com/speed/public-dns/docs/using

But why WOULD I want to do this?
I used to think it had some advantage. Is there really?
There is meant to be some performance improvement although I never really intentionally change the settings myself as my ISP's DNS servers work well.

I do have a few machines that use them for the simple reason that they have static IPs and it's easier to remember "8.8.8.8" and "8.8.4.4" instead of my ISP's IPs!

OpenDNS is a bit different as it gives a lot of control - I've implemented them in the past to create a simple content filter on a network used by a Youth CLUB, it's not the most SECURE since changing the DNS settings would bypass it but the machines are locked down so tightly that regular users can't change the DNS settings.