Thanks for the bug reports folks. Looking into it
During testing the game was able to run on the following hardware:
iphone 3GS - 4.0.2
iphone 4 - 4.3.1
iphone 4 - 5.1.1
ipad (3rd gen) - 5.1.1
ipod touch 8GB - 4.2.1 (some textures not displayed due to armv7 requirement, but ran fine on armv6 builds)
Memory management looks like the primary target as has been suggested.
Could folks with issues please post the iOS version for their hardware.