Giving this a bump since I received this e-mail myself over the weekend, as did at least one of our other developers.
If dyn.com is worth it for you, upgrading to their paid service is certainly worth $10 for the first-year offer. The $25/yr after that is still not a bad price, just over $2/month.
For me, I moved my hostnames to namecheap using my own personal domains. I'm already paying Namecheap to do my domain registrations, which are $8-10/yer depending on the domain, and since they also handle my DNS, DynDNS through them is essentially free to me since there is no cost from them aside from the domain registration. That's cheaper than going through dyn.com for just DynDNS.
There are other free providers out there, it would be nice if others who have experience with them would give reviews/opinions on the other choices to see how great (or annoying) they are.