At the risk of using up my personal allowance of agreeting-with-Lovejoy moments, I agree with Ben.
We bought a GPS earlier this year because we're doing a big tour in a month or so and wanted something especially to help us get out of French cities. (And we wanted a toy to play with).
But we're taking a big pile of maps too, because you don't get a sense of place without a map. The GPS got us very effectively from home to Cambridge last week - at least until we realised we didn't know exactly where in Cambridge we were headed and had to follow our noses. But although we could get a sense of the changing landscape (hilly, less hilly, rolling) we couldn't contextualise that landscape (we thought we were going to go through Hitchin, until we discovered we were past Hitchin).
It's also a pain in the neck doing route planning. I tried planning a route last night between Bucks and Portsmouth using only bikehike.co.uk and the GPS maps. It's horrible - you get no sense of the big picture, only of the small detail. When someone invents a portable 40" high-resolution waterproof screen I might be persuaded to ditch the paper, but not until then.