Not sure if it qualifies as hand held or not - it's actually wrist-held...
Anyway, I've been very happy with my Suunto Ambit 3. It's a GPS watch. I'm able to load routes/tracks from HAZ onto it and, though I thought it was kind of cheesy at first, I actually like the interface for following a route better than that of my old Garmin eTrex. The Ambit 3 simply provides you with a line representing the track (no basemap or terrain markings) along with an indicator showing where you are relative to the track. If that indicator is on the line, you're on the track. Otherwise, you're off and you simply need to travel in a direction orthogonal to the line to (try to) find it again.
A major drawback to this interface is that it doesn't provide any indication of which direction is which. This is only a problem if you're confused about which way you're going. That said, it's happened to me a few times. It appears that some of Suunto's newer offerings have solved this problem by showing the route that you've traveled so far on a color display.
I used to use one of the Garmin Fenix watches. I stopped using it because its calculation of the distance traveled was horribly inaccurate in trees or when on the side of a hill or mountain. (I did Derrick Trail - Horton Loop which is only 8.8 miles in length; my Garmin Fenix 2 showed a hike length of over 13 miles.) The only time I have similar problems with the Ambit 3 is when I go into narrow canyons. I'm guessing that most GPS devices have problems in this type of situation.
I used to bring a handheld GPS with me for backup. I've stopped doing that, though I do use my phone when I need to look at a map.