GPS Stagnation
As far as I can tell, hand-held trail-style GPS units peaked with the Garmin GPSMap 60csx. Pictured is my old GPSMap 60cs (no 'x') on the top of Mauna Loa. It is rugged, beautiful and functional.

Since its release Garmin has produced iPhone-style GPS units with touch screens and pretty, colored icons, but they can't begin to replace the 60csx. For instance, I installed a 1GB microSD card in my 60csx. Every time I'm on the trail, my location gets written to the card. I couldn't fill the gigabyte card in a lifetime of walking. I can't do any mapping on the unit based on the data stored on the card, but when I get home I can pull off my complete track log - no worries of using up the GPS's entirely inadequate 10,000 point tracklog memory and having the start of my trip erased. Even the high-end Oregon and Colorado units don't improve upon this 10k-point limit, and they don't write their location to the microSD card.
Aside from my concern about damaging the pretty LCD screen of the Colorado while throwing it around on some mountain, if they only added the ability to record the tracklog points to the SD card, I'd probably buy one. Such a shame.
