'Then would you be happy to use instead of a regular GPS? '
No definitely not...
Whenever I have bought anything other than a proper aviation Garmin unit I have invaribly been disappointed.
The main thing is though not to fly totally reliant on any one GPS navigation system, whatever the variant, always have a backup,even if it is only a chart with line on it and navplog and stopwatch.
Skydemon is good but only IMHO for use as a backup system.