I have the same problem as others. My progress is not being saved when I exit the game. However, I have not had any crashes. I played last night for a few hours straight and finished several of the Conquest skirmishes. When I opened the app today, my progress was gone. I'm asked each time if I want to play the tutorial. I'm on an iPad 2, current iOS, nonjailbroken.
And, I agree with a previous poster, the buttons are way too huge. They could easily be cut in half and still be functional. Also...pinch to zoom. Then you could get rid of the +/- buttons. The layout is definitely not optimal. But, the game is fun, so I hope Slitherine will address some of these comments in future updates.