The most important things for me on my bike are:
- Power in watt;
- Heart rate;
- Kilojoules (or calories);
- Elevation and ascent.
So Strava is not for me, since it has no power or heart rate or kilojoules.
But there are plenty of riders out there who are just using distance and speed and GPS tracking and who already have an iPhone. Just watch out for battery drain.
What I really want is a live rear view camera overlaid with statistics on power heart rate, etc and real-time graphs of those items, along with the usability of an iPhone. Now that would be cool.