I usually use my Samsung Galaxy Player which is an Android device, but is not a phone. I prefer it because it has better battery life than most phones. It can last a full day of skiing.
I usually use my own app, Ski Buddy (http://k0gappsw.com/ski-buddy.html). It is a simple app which gives your speed, distance traveled, altitude, and other info to you in real time as you ski by speaking it thru your earphones. When I am skiing, I am usually most interested in knowing: "How fast am I going now?". This app gives me a good idea of that.