For all the club members who have recently ventured into the Apple orchard by purchasing an iPad or iPhone, you can find an interesting comparison of many of the mapping apps on this wiki.
I personally have used the GalaGPS app which worked beautifully in Turkey when walking The Lycian Way. This app allows you to store on your iPhone/iPad map tiles so when you are in a foreign country you do not have to use expensive roaming data.
In the UK I use ViewRanger a local Cambridge company! and MemoryMap both allow you to purchase OS maps etc. (MemoryMap allows you to import any maps you have previously bought from them on CD’s for your PC).
A vital point to remember is that the iPhone/iPad inbuilt GPS system only works well with a cell tower & or a WiFi connection. Do not use as a primary navigation device in remote areas.
However, they are incredibly useful devices for regular walking.