Me too - I only do audio recording + VST instruments (mostly AD2, Kontakt, East West), no synths, and I'm just feeling my way without the manual and following the rookie questions now appearing on the Cubase forum. (I usually find manuals tend to tell you what menu items do, rather than explain specific processes). So I haven't done anything too demanding. Mostly it's a case of getting the mind-set of the workflow, and that's fairly similar to Sonar.
I've redefined a load of keyboard shortcuts. Cubase seems to have a a great reliance on remembering the difference between ctrl, shift and alt keys for shortcuts. I use PRV a lot for VST instruments and I miss the smart (star) tool Sonar had.
There's also the audio recording over/following an existing audio take issue - that seems to be getting some airplay from Sonar refugees on the Cubase forum. There's already a feature request submitted for a Sonar approach to that; even so, it's not a huge issue.
I do enjoy using Cubase, and even the dongle doesn't really matter. If I'd invested that amount of technical development, I'd want to protect it too.
Sir William - I hope the health scare works out well.
Mike - I hope the PC gets sorted.
jdf