For some reason when I didn't have a signal I couldn't use the GPS to get directions when I was lost on the way to a race a month or so ago. I guess it was just my iphone and the iphone that belonged to the guy I was with.

I'll keep my Garmin, it works great with my powertap and my quarq.

One other point, if I crash and ruin my Garmin I just buy another Garmin. No contracts to sign, no worrying about not being eligible for an upgrade, etc, etc...