The COMAND sat-nav is certainly not as good as it could be. Better use of the huge screen needed and the instructions for large roundabout style motorway junctions are annoying.
Approaching the motorway junction where I essentially need to go right, it says "prepare to turn left" or "prepare to turn half-left".
The satnav we had in our C204 seemed better.
Other than that, the interior in the S205 is excellent, and I was someone that didn't like the iPad on the dashboard beforehand.