This mobile version capitalizes on the environment it is placed in, using the iPhone's built-in features to offer control. For instance, to adjust the angle of your view you actually tilt the phone itself. Navigation can be done using hand gestures as well, common for iPhone applications. Other features include geo-located Wikipedia articles and an instant “location” feature that will zoom in to where you happen to be standing at that moment.
From the included video in the blog post, the picture quality looks decent, about on par with the PC, though I doubt the actual speed of loading would be anywhere near what is demonstrated. The iPhone has been criticized in the past for slow download speeds, and Google Earth is definitely not a bandwidth-light app.