I just completed an upgrade of this site (and the url-master.com demo site) to DNN 7.0. I have also upgraded this blog to use the new 5.0 DNN Blog, which brings with it the change to no more anonymous comments. Sorry for those who don't like to sign in to comment, but the need for social interaction requires contributors to have an account!
The upgrade went smoothly and took about 5 minutes from starting backups to looking at the new site. The skin on this site (yes, needs updating!) was designed for DNN 5, and never quite worked properly with DNN 6. But I'm happy to say that everything looks great with DNN 7, and the new control bar really is a great thing.
If you haven't yet upgraded to DNN 7, I would plan to do so. Just remember you need to have IIS 7 and .NET 4 on your site before you set out, and always, always, always have a backup prior to starting.