As you may have noticed, we silently launched a new iPad version that includes IAP, new towers, new items, along with a free trial version so people can check out the game. If you already have the full version, you can get the new Polymorph Tower (turns enemies into hobbling barnyard animals) for free by also downloading and opening the free version (Fieldrunners 2 HD Free).
We launched these iPad builds silently before pushing out a matching update for the iPhone version (along with a free version of that, both of which include iPhone 5 support) to make sure things were bug free. Unfortunately, we immediately found game breaking bugs iPad version, and these bugs are also present in the iPhone versions. So, we're submitting new builds now and hoping to get it rushed through the submission process. Sorry for the inconvenience, I know this is pretty lame.