I have a Garmin iQue 3600, the combination Palm PDA and GPS. It came with City Select V5, and I need to upgrade one of these days.
To the level of paved county roads, navigation is excellent. Once you get to things like Forest Service roads, it starts getting iffy. However, at that point, I can start depending on my topo maps instead of the iQue navigation.
For instance, finding the Henrys Fork trailhead for Kings Peak in Utah, it knew about the road that Henry's Fork Campground is on, but not a couple of the intervening roads down from the Wyoming line. Still, it got me close enough to be useful, and was immensely helpful navigating through the maze of freeway interchanges getting out of the Salt Lake City airport and onto the Interstate running up into the northern corner of Utah and on into Idaho.
I think you'll find it very useful, within its limitations. (It is terribly funny when a road is re-routed and the CS database has the old road...it gets all upset when it thinks you're driving off through the woods...there are several state roads here in MO that have been straightened since I got the iQue, and driving along them with the iQue navigating produces some very interesting directions!)