Never use your domain registrars DNS, bad idea IMO. Use your hosts DNS to eliminate the number of points of failure as evidenced with Godaddy's failure today. Not to mention the fact that my host provides way better DNS tools and they can totally diagnose any DNS issues that occur without any fingerpointing between them and the registrar.
However, aside from the above consideration, a good 3rd party DNS provider if always a good idea so if your host goes down, and hosts have gone down for days, you can rapidly switch to a different host.
If you haven't done it yet, today is a good wake up call to check your TTL settings and see how long it would take you to actually move your site if you needed to do it. Many of you might find out it could take hours, maybe a whole day. Worth a look for your primary money making domains at a minimum.
They kick and scream for more power citing "potential cyber terrorism" but when millions of sites do go down all at once... not a peep. Very suspicious.
What's suspicious? They're obviously heads down doing what they should be doing in this situation...
... posting "neener neener we told you so" on Twitter. P.S. After the big SOPA flap, why are you all still using GoDaddy?