Tris
SkyDemon is great - but you do have to know and mitigate against the limitations of using GPS on consumer devices such as batteries running out, overheating (iPads!), sunlight, software crashing, satellite failure / error without WAAS (many devices were displaying 50km out a few weeks ago after a GLONASS failure).
I always have a non-electronic backup as well, especially when travelling away from where I know (print the PLOG, write on it as I go, have a map perhaps with some lines on it).
Flight planning wise it makes VFR flying much quicker and easier.
In the air it is a useful tool and certainly one of the best "consumer" level products. Their own device has few (if any) advantages over buying a tablet and installing SkyDemon on the tablet.
I have a cheap car sat nav which I installed SkyDemon onto and it works well for what I use it for and has all the features that their branded device has (other than a poorer screen).
note that I believe that Sky Demon can export files in a format compatible with Garmin (and other) installed devices.