Playing iPad3, 5.1.1
Like the previous reviewer, I have the same problem with swipes not registering. It mainly happens right after you grab loot on the screen, then for some reason your swipes dont register, resulting in death.
The game play is a bit odd. The invaders first run past you with a arrow on their shield, you swipe in the direction of the arrow, then it looks like they run past you again. But the second time around they slow down, and the fight initiates...
I think if I want to go further in the game I will have to stop trying to grab loot, and just focus on following the arrows...