I've found a consistent crash for me, although it didn't seem to always do this.
If I'm playing in the Tower or the Mine, and the phone goes to sleep, when I slide to unlock the screen comes back up but immediately locks. I can't move, and I need to force quit which dumps back to the apps screen.
After this, Aurora Feint won't launch unless I restart the whole phone.
It's happened about a dozen times now, and it seems always linked to the phone going into sleep.
I re-confirmed this after some clean reboots and general play without crashing.
In the tower, working on Molten Lava, the game goes to sleep. I wake it up, and animation continues (because it was a different rotation than I left it), and the animation hangs part-way during breaking. At this point, the game is hung, phone needs a hard-reset to turn off.
I have this problem also. I just stop the phone from going to sleep. If I have to stop playing, instead of letting it sleep, I hit the home button and exit out of the game before going to sleep. This seems to work for me.