I think most GPS devices (dedicated ones like Garmin, TomTom don't have digital compasses. It doesn't cost anything to use the GPS, AGPS just helps the GPS get a lock-on quicker.

One problem I have noticed is that the GPS can get stuck on sometimes (especially with Ovi Maps since if the program isn't closed gracefully it'll leave the GPS on). Disabling the GPS in settings won't do anything, only a reboot will actually shut off the GPS. For now I just don't bother with Ovi Maps and instead use the maemo browser + geolocation add-on.

Edit: Oh another fun Ovi Maps bug, there was this one time I opened it up and after it got a GPS lock it said I was in two places at once. One GPS dot said I was at my home address, while the second GPS dot said I was at the Donut shop (correctly). Yet if you tried to plot or lookup anything it would use the GPS of my home address and not the Donut shop.