Since when does trusting a business critical function to a free service make any sense? At least GoDaddy has a motivation to provide some level of service because people are paying them.

Some other alternatives that aren't free, but are highly reliable are: http://dyn.com/ http://www.dnsmadeeasy.com

I use the latter one and in addition to providing an alternative to my registrar, they also seem to have much faster response times, which cut some milliseconds off a site lookup.