Anyone use an Edge 510?

My old Edge 500 is crapping-out, so I'm looking to replace it. I've looked over DC Rainmaker's reviews, now I'm looking for B.T.'s opinions. I'm (finally) getting a "smartphone" and like the idea of pairing the Garmin with my iPhone, but is that option actually as functional as it seems? Is the touchscreen a help or hindrance?

Opinions?