After playing it for a bit last night, I'm very impressed with the game play.
The lack of a little direction controller on the ipad usually makes them a pain in the arse to play, but this one worked okay for me and the auto target works well.
I think this platform could be built on. Perhaps a Dredd version without Zombies

or 'swap out' the graphics for other characters.
The beauty of iPad games is that they can be updated by download, so if this starts getting a bit tired, they can just create more levels or upgrades to keep it interesting.