For my solo backpacking trip to the Desolation Wilderness, I downloaded the Yodel app as a way to keep in touch with the crew back home, let them know my backpacking itinerary in case anything happened, and update my whereabouts along the way.
The main function of the Yodel app is to send alerts of your planned activity, including when you plan to return, as well as updates of your location along the way. You can choose to whom you would like to send the alerts and whether you would like to send them by email, SMS or both.
Upon arriving at the Echo Lakes trailhead, I sent the initial alert with my planned backpacking itinerary, as well as my estimated return date and time. Here I encountered the first problem. Even though I planned to return to the trailhead two days later, the alert declared my planned return time as the afternoon of the same day.
After setting out on the trail for the day, the first few alerts went well, sending both an email and SMS updating my exact location. I had somewhat good cell coverage for the first part of the hike, at least 2 bars with either 3G or Edge (E) data service, enabling me to send both emails and SMS.
Later on the trail and unbeknownst to me, however, the alerts I was sending from the Yodel app were listing my location as downtown South Lake Tahoe. By the time I reached my first night's camp at Lake Aloha, I had run out of cell coverage so was unable to update my location to let my family know I had arrived safely at camp. Needless to say, the family started to worry a bit when they couldn't reach me by phone and were being told by the last alerts that I was off the trail.
Bottom Line: Sorry Yodel, you are a nice little app but nothing I would pay $0.99 for again. I would recommend instead that if you are heading to an area with good cell coverage, you can just as easily use the Google Maps app to both email and SMS your exact location. If you are traveling to an area with limited cell coverage, I would recommend using a satellite based alert system such as SPOT or Delorme.