I have a Garmin Colorado GPS and it says that it has a "barometric altimeter". Barometric altimeters are OK if you can reset them every day at the exact altitude you're at but that's a hassle.
Why the heck can't we have altimeter readings from the GPS sattelite constellation??? Today while backpacking in the Spring Mountains north of 'Vegas my Colorado altimeter said 9,860 ft. and my buddy's altimeter said 9,780 ft. and we both wondered why Garmin uses a barometer for an altimeter.
"There are no comfortable backpacks. Some are just less uncomfortable than others."