I've been using Garmin GPS for years, most recently the 60 series.

This weekend I downloaded an iPhone app (MotionX GPS) on an iPhone 4S. I took them out side by side for a long hike this weekend and I was very impressed with the app. I was hiking in the East Bay hills in the SF Bay Area.

First the iPhone display is light years ahead of the Garmin in terms of quality and detail. The base maps were also superior in terms of the details they offered. I purchased the Garmin Topo for Western US 24K. To use Motion X when you're out of cell phone range, you have to download area maps, but this was quick and easy to do. You go to a map and draw a circle of the area you want to download. I downloaded about 50 square miles of maps in 10 minutes via wi-fi.

Both were about the same in terms of speed in acquiring satellites and maintaining contact even canyons with tree cover. The claimed "accuracy" was about the same, but Garmin more often claimed accuracy under 20 feet, when the Motion X would be claiming 30 feet or so. At the end of the hike the Garmin said I'd covered 8.42 miles, MotionX said I'd covered 8.38. I think that variance is within the tracking errors of each. Also one time in cover the Garmin said it could not acquire a signal while the MotionX claimed it had a signal. This was very surprising to me, given the 60s reputation.

MotionX did worse at speeds, it said my high speed was 22 miles per hour, and I don't go that fast even falling down a hill. This caused my average moving speed to be a bit higher on the MotionX (2.7 vs. 2.6mph) This could also be a function of the shorter distance measurement on the MotionX.

The only downsides I can see to the iPhone as GPS at this point is that it is not as weather resistant as the Garmin and you can't swap out iPhone's batteries when in the woods (but I think 3rd party charging devices might solve the latter.)

I'm curious about others' experience with the iPhone as their GPS and recommendations for other apps.

My Garmin Oregon and my Garmin eTrex Vista HC hold a signal in dense woods, but my iPhone 3GS wouldn't. I think the antenna was degraded a bit recently, sometimes it would get inaccurate with just a light cirrus cover. My new iPhone 4S seems to hold a signal a lot better, but I haven't tried it in the woods yet. I'm mostly using Runkeeper on my iphone.

I've been using iTopoMaps and been very pleased with how it performs. As a dedicated wildlands GPS, the iPhone isn't sufficiently rugged, but as a backup or for casual use on and near marked trails, it's been great. I drop a waypoint at camp, another at the trailhead, and off we go.

(No affiliation to Apple or whoever the publisher is of iTopoMaps other than as a satisfied customer)

I'll echo your experience. I'm using MotionX GPS HD on my iPad for hiking and city walking; and MotionX Drive HD for driving. They are both superior GPS apps. I too have noticed that the iPad holds a signal better than my handheld GPS, an old Garmin eTrex. I also note the absurd Fastest Speed numbers in MotionX.

I'm jealous of your iPhone 4S! The iPad is my first iOS device but I see an iPhone in my future. I have heard that the iPad GPS is more sensitive than the iPhone's. But it would be a lot easier to take hiking!

The weather resistance is important to me, but I've been wrapping my iphone in a zip-loc bag when out and about, and it's not WATERPROOF in that setup, but it rain-tolerant.

My experience in terms of GPS signal lock, map quality, etc. is the same. I use a Topo app (can't remember name at the moment) and it works the same way - you preload a bunch of maps and it works even where there's no cell service.

I still think that the "dedicated" GPS devices are tougher, but the user interface on the Garmin and Magellan devices just can't hold a candle to the iPS user experience. Android devices are nice too.

As far as battery - there's a universe of external battery options, I have a gizmo that gives me USB ports with just AA batteries, and that works. I also have external spare batteries for the iOS gizmos in my life.

I have the iPhone 4, but no trail apps. I don't get good cell tower reception in the areas I hike.

Are you saying w/out a cell phone signal your still getting GPS accuracy to 30ft?

Or better. And iTopoMaps and MotionX let you download maps for offline use.

Thanks for this. I just may purchase the app

Yah, I had an older Garmin eTrex Vista, the Vista HC is far better. That's what the "H" is for, high sensitivity.

If you want to add a bit of weather protection to your iPhone, try the Otterbox Defender case http://www.otterbox.com/iPhone-4S-Defender-Series-Case/APL2-I4SUN,default,pd.html?dwvar_APL2-I4SUN_color=20&start=1&cgid=apple-iphone-4s-cases It adds bulk but no real weight and you can access all the functions with the case on. The screen is a bit less sensitive in the corners with it on but still usable, the rest of the screen well you wouldn't know you had it on. I haven't tried it in really bad weather yet (curse this sunny Australian weather :-) but it looks like it should be ok. You can get them in a camouflage cover, just don't drop it.