+'s and -'s
iphone w/ motion x: compact, not redundant, it's a phone! it has apps! it works But, a) you hard to see it, b) you need to have a cell signal (which is VERY iffy here in New England)! I use to look at the map of the "big picture" of where I am going...
Garmin Etrex handheld: compact, "waterproof", great for "off-road", but a) hard to see, b) lousy user interface, c) a pain to download to, d) takes batteries. I use for my off road adventures.
Garmin Nuvi GPS: big screen easy to read, don't need cell signal, but a) not waterproof, b) not too good for "off road", c) big and not as portable.
Experience is something you don't get until just after you need it.