The iPhone app was really the reason I got into geocaching too. I'd heard of it before and it sounded interesting, but was never motivated enough to make the initial investment in gps. I found the geocaching app and thought "hey, it's only 10$, I'll give it a shot", and it's been a lot of fun. I do it mostly for the outdoors aspect..I'd rather hike a few miles and find one cache than find 5 micros that are 10 feet from the car. I've since picked up a Garmin 60cx, but that's only because the iPhone can be unreliable in the woods. It has worked for probably 85% of my attempts, but I don't want to hike a mountain and not get the cache because my gps couldn't get signal. The iPhone isn't the end-all-be-all geocache tool, but it's awesome for getting people into geocaching, and for the convenience of access to the site on the fly.