But the potential places Battlefield 3: Aftershock could go have me genuinely excited for what might be.
Right now, there really isn't a game plan for Battlefield 3 on iOS. Full multiplayer support over WiFi and local wireless have made it into EA's admittedly vague hopes for the game, and the publisher is also toying with a dual currency scheme -- grind currency (your time) and premium currency (your money). Ideally, in-game currency would unlock different kits and weapons.
Players will have persistent gear and levels, much like Battlefield 3 proper -- but most of the menus I saw had placeholder art and descriptions, so it's hard to be sure of what will be in the final product.
It's fairly certain that Battlefield 3: Aftershock will have separate single-player and multiplayer components, kind of like what was on offer in Battlefield: Bad Company 2 on iOS. There will be a campaign mode that plays like Horde in Gears of War (e.g. waves of enemies come and you shoot them), but the multiplayer scope this time is a bit bigger. Battlefield 3: Aftershock will have a competitive multiplayer experience that aims to be on-par with its console brethren, but it wasn't available for me to check out, sadly.
Battlefield 3: Aftershock is still a long ways off, and its look is sure to change drastically on its way to the iTunes app store, but what little I saw showed overall promise. It wouldn't be the first game on iOS to offer competitive multiplayer in this fashion nor a single-player campaign, but with the right resources, EA can certainly make it one of the better, more fun-to-play time sinks out there.
I suggest starting with a good look at Modern Combat 3.