Free download for demo version and it has the full game as an in-app purchase. No "full game without in-app purchase" app is available.
Full version is $5, but is currently at a launch price of $3. The description doesn't say when the launch sale ends.
The description says "This is a Universal App. Your in-app purchase DOES cover multiple devices on the same account."
Download size: 95.6 MB. Size listed in iTunes: 113.4 MB.
3 save files. There are Copy and Erase options.
Some things are noticeably higher resolution that the DSiWare version, such as character portraits and your life hearts.
I read that they adjusted things to make up for having virtual controls, like making some platforms "a little bigger." I am not going to go compare everything. :P
Control changes: The DSiWare version had an Always Run option changeable by pressing Select: run and hold Y to walk or walk and hold Y to run. There is no Always Run option in the iOS version: you always run. The girl left of the save house in Scuttle Town told you about the Always Run option, but in the iOS version she only says she loves running.
For some reason the item button is at the top-left corner of the screen. (There are attack items. Attacking is usually with your right thumb, because your left uses the d-pad/analog stick to move...)
The Action button does the following: Attack. Talk. Form-change dance, by holding the button (Shantae attacks first). Which means no walking. But monkey form doesn't dance, so you can walk with it...
The Dash button changes into the Mode button when transformed: press it to change back to human form. (I should mention that this game's "dash" moves you backward and is for dodging, not running.)
The Stuff button is the pause button and is for accessing your inventory. (In the DSiWare version your inventory was accessed on the system's touch screen.)
In the DSiWare version you can skip conversations with Start. There seems to be no way to skip conversations in the iOS version. However, the next part of a conversation appears instantly when you tap the screen, so you can quickly get through conversations by tapping away. In the DSiWare version, pressing A caused the next part of the conversation to be "typed" (though at a rather fast speed for typing) and you had to wait for it to fully appear before you could go to the next part. Not that it mattered if you wanted to just skip it with Start.
(It should be easy to find a screenshot of the game if you want to see the button layout.)
That's everything I can think of. --- "Please... never do anything as crazy as that again...." "...I'll think about it."