I have tried both an HTC phone, not sure what model and my iPhone 3gs. Granted newer tech phones have better battery life however they also come with a steep price tag. My phones cost me nothing up front, just a two year extension and my cell rates are somewhat competitive considering the free phone. Where I live and ride is very rural and low density population. The phone is often using battery power searching for a signal and the gps based apps also suck battery power. Runkeeper, MapMyRide and Strava all impact battery life about the same. When i used my phone to track rides I had nothing running in the background, just the phone and the cycling app. I was having problems with apps crashing with the HTC so I "upgraded" to the iPhone, only to experience the same app errors. If anything the HTC had a better battery.

My point is I've used both and for me Garmin has much better battery life. It also if you buy the mid level or higher has other valuable add ons such as HRM and speed/cadence. I works for me. I'm glad your phone works for you.