The GBA had the right controls for JJ gameplay; it's the fact that GameTitan messed with the formula that screwed it up. Replace the carrot grenade with a run button and get rid of diagonal shooting and voila! In addition, while the GBA might not have been able to handle something like JJ2 properly, JJA isn't exactly pushing the system's boundaries; it could've looked a lot better.

That said, iPhones and iPads are about as suitable for gaming as this thing.