I went on a ride couple days ago and used the .99 cent MotionX iPhone app as my GPS based cyclometer and my friend used his Garmin 705.
Honestly I can't tell the difference. Our data was almost exactly the same. And my elevation numbers actually seemed better.
Love that the maps are 100 times clearer on the iPhone. The app let's you pick from MitionX maps, Bing Maps, and Goigle maps. Also displays satellite and terrain maps. Only draw back us that it won't do turn by turn directions. But who cares. Phone has google maps for that.
You can even upload you map data to the web.
I don't have a handle bar mount yet, so it just ride in my seat bag and I used my cateye for general speed numbers.
Anyone else do this?
Why spend $300-400 on an expensive Garmin? (yes weather proofing is an issue).