With GPS I do look more outside, since I feel more confident of my position. I still fly map and compass, but on longer flights in unfamiliar airspace I put on GPS to check I didn't mistake that one road for another.
The thing is, GPS is not taught for PPL and therefore many people don't use it as should be. 2 or 3 flying lessons at the end of the course would be good, with emphasis on the use of it as standby instrument. But it can help you in those cases where it is too busy to enjoy the flying itself.
GPS is what navigation should go to, imagine people in the 30's saying no to VOR navigation for the same lookout reason.