For VFR flights, the primary means of navigation is, and always will be, looking out the window. As long as that primary means of navigation remains, and continues to be taught to an appropriate level, there is nothing wrong with backing it up with whatever other aids happen to be available, and GPS is a great tool for this.
For IFR flights, it is again useful, and probably important, to use as many navigation aids as possible to back each other up. So if you are following a radial from a VOR, there's nothing wrong with following that radial, and having a line on a moving map GPS to confirm that the VOR is working correctly - or vice versa, following a GPS track, and having the VOR tuned and the CDI or OBS centred to enable you to cross-check the VOR.
The problem with both VFR and IFR operations is that modern GPS is so easy to use in its simplest form, and so flexible once you start going into more detail, that it is very tempting to use it as the only means of navigation. For VFR flight, this results in lack of situational awareness, since you are no longer using your primary means of navigation. I got caught out by this just last week. I was P1 on a flight which I intended to make IFR, but on the day we decided to depart VFR from an airfield which I am not familiar with. I had the route programmed into the GPS, and followed the GPS route. ATC asked us to report abeam a certain town, and I realised I had no idea where the town was, and didn't have a chart to hand. Fortunately, there was another pilot sat in the right seat, who located the chart and pointed out where the town was, thus keeping my workload to relatively low levels.
For IFR flight, the danger comes on the rare occassions when the GPS fails and you are left with little awareness of the navigation aids around you, none of them tuned in, and hence no way of fixing your position without a sudden increase in workload. But if pilots are aware of these potential dangers, and ensure they don't fall into the traps, then GPS is one of the best tools modern aviation has.
FFF
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