I've had a server with Dialtone for a little over 2 months. Their Server Interface is pretty good. It automates all new account creations and allows you to set quotas, add DNS entries, add email accounts, change IP's associated with a domain, etc.. All in all, it does the dirty work for you.
The user control panel is very minimal. It allows my end users to create autoresponders, email aliases, and to install FrontPage extensions.
Its not bad but pretty basic. What you get when you get DI servers is quality equipment at good prices. If your looking for something to take away the admin functions at the command line or give you users good control panels then you probably want to look elsewhere like alabanza. I dont use alabanza myself becuase they are quite a bit more expensive but the panel is designed for hosters.