Well my main concerns stem from the fact that i'm used to Android.
Whenever i'm looking for a menu (to change settings; bring up suggestions etc) my instinct is to go to the menu button on android. Obviously iOS doesn't have this button, which is fine, but every app has their 'menu' button in a different place.
Secondly, the 'back' button. Sometimes i've clicked on the wrong thing, or just want to go back to the previous page/app screen, and in order to do so, you have to find the 'back' button, which is usually in the top left, but sometimes in the bottom left etc.
Again, it's just because i'm used to Android, but i do think that the menu button in particular is a good idea. Each app can put whatever menu items they want in it, but you always know how to access it whatever screen you're on.
I realise that the iPad 1 is almost 2 years old now, but we wiped it clean when we got it and it's still quite slow....does it not work very well with iOS 5.1? Maybe we should have stuck with 3.1.