From memory jaguar use Tandy electronics from 1972 for their satnav.
I'd be tempted to update the maps in mine if :
a) The update software didn't just bomb out with an error every time I try to do it
b) It was capable of sending me down roads that don't have grass growing down the middle. Maybe mine has the mud-plugging Land Rover version installed by mistake?
Not had any issues with hers, but hers is the poor mans version (DTM will know the exact designation) that you plug the SD into a computer. I'm guessing yours is the OTA update version?
As for routing decisions, hers is set to default I believe, and slightly favours major roads, and has never taken us a silly route, even if its not always the route I'd personally take.
Biggest gripe is the voice control for the Navigation part seems less comprehensive than I think it should be.
My XJ is the HDD gen2.1, which sadly the maps are no longer available for, and needed a bit (not much, there are only about 3 settings) of config to get decent route planning. My biggest gripe beyond the lack of maps now is the TMC settings aren't granular enough - the options are off, any alert, or very major delays.