I've been promising it to myself for a decade and I'm pleased to say I enjoyed every minute. 15 nights in 9 different cities and an average drive of 3.5hrs between them, Longest drive of 5.5hrs on the way back, but helped by Mrs S, who also loves driving.
The drive from Switzerland to Italy was a highlight for me. Lovely twisty mountain roads and amazing views, with snow in places despite temps in the low to mid 20's.
Highly recommended, but planning (and saving up!) are essential.