I used a Hollux on a PDA (very good) until I bought my I-phone. I have been surprised and impressed how good the GPS is on the I-phone. though and I use it most of the time now. I never used a GPS until I began working in Western KY and Southern IL; with no landmarks to reference a map to a GPS can come in pretty handy. If you have a phone with a GPS you may already have what you need. I still carry TOPOS and a Compass in my daypack though because I don't like to rely on batteries.