I don't use the GPS functionality other than on the odd occasion for interest sake. I have both Jeppesen FD and OzRunways. I'd be quite pleased if my employer dropped the requirement to use Jeppesen, as then I'd go to OzRunways/AIP solely.
The Jeppesen airways manual is a dogs breakfast. Two separate manuals covering the whole world, so finding what one wants can be quite difficult. It is NOT just an electronic version of the Aus subscription paper airways manual. Further, it doesn't have an amendment list to draw ones attention to changes from one revision to the next!
Despite being almost 2 years old, Jeppesen FD still cannot reliably accept a route entered with airways designators. This is because where a VOR and an NDB share the same identifier, say AS, the FD App defaults to the NDB, which is not part of the airway (the airway using the VOR). For example, instead of being able to enter the route between Alice and Cairns as "AS J64 CS", on has to enter "AS ANZAC J64 BIB CS". AND, there is no save function, so the route has to be typed each time it is used.
Compare this to OzRunways, the AIP is also searchable (though deciding which result is the desired one can be difficult, one can scroll through the pages, note the change bars and therefore easily see what the changes are since the last revision. ERSA is included.