Memory Map on the iPhone 3
Just my view here but I bought the Memory Map data CAA 1:500,000 for Scotland for use as a backup on my iPhone.
Whilst it might be OK on an iPad, the iPhone screen is so small as to make it almost useless. the zoom function does it in steps so you cannot get the map displayed at an optimal size for you - it either steps up or down a size (too big or too small).
I tried it in the air a couple of times and frankly the iPhone is not up to it, it takes ages to get any kind of a fix and is too unreliable even as a backup.
Waste of money in my view - Having said that I may be in the minority here.