Cool, I just upgraded from my 1st Gen to a new 3GS, so unused to the GPS features. So far, I discovered that the GPS chip eats battery life unbeliveably fast.
Yeah, we've found that we can record a track for about 4 hours with Gaia GPS. We use the proximity sensor to turn the screen off, so if it's in your pocket the screen won't be wasting energy, but it's definitely the limiting factor for iPhone GPSes. I've been testing a bunch of solar charging solutions while backpacking. I'll write up a review soon.
My suggestion on features for folks like us ExPo types that trust maps is to include a soft button to turn on/off the GPS function on the fly. Ideally, I'd like to use the screen map & compass to navigate from region to region, then click on the GPS for a quick fix to confirm my navigational ablity, turn it back off and move on to the next landmark.
I'd love that feature too, unfortunately turning off radios uses Apple's 'private APIs', and they won't approve apps that use them. But unless you're recording a track, after getting the initial position, we set the GPS to a pretty low accuracy threshold, so it doesn't use so much battery. There's a button on the map screen to force an update when you want one. I'd also like soft buttons to turn off bluetooth, 3G, and wifi within the app, but it's not possible.
I'd also like a free trial version, even just a 14 day version would be good.
We've been thinking about how to do a free version. Apple doesn't allow time limited versions. But we were thinking about limiting it to a few map downloads, short tracks, and maybe not full zoom on the maps. It's kind of tricky, since you're not allowed to have anything in the app promotes the paid version, like saying update for more map downloads.
