My intention is to provide a review of the PN-40 from my perspective, that is, from the perspective of a hiking who does a lot of bushwhacking, off-trail hiking, and abrupt roadside/trailside photography. In terms of a GPSr, in my mind the needs of the bushwhacker fall somewhat between the needs of the geocacher and those of a trail hiker. The bushwhack hiker needs to have the ability to accurately navigate off-trail to a fixed point (like a waterfall) or a series of fixed waypoints, like a geocacher. The bushwhack hiker also needs the ability to record an accurate track, to allow for a return, like a trail hiker. Where the bushwhack hiker experience differs is that often, the bushwhacker needs the ability to make more fluid decisions, which is why so many bushwhackers have rejected the GPS as a navigation device, and have retained their topo maps. To bushwhack you need to be able to visualize the terrain ahead of you, since you often need to make decisions regarding potential routes suddenly, usually because your planned route didn't pan out.
DeLorme is a fairly new entrant into the handheld GPS market, as the PN-40 is only their second GPSr, succeding the outwardly similar PN-20. DeLorme has been making GPS products for a number of years, and they are primarily a map company, so it wasn't a huge leap for to enter the handheld GPS market. DeLorme's map company heritage means that unlike most handheld GPS units, the maps come first.