I will repeat my impressions which I posted earlier in the thread.
The game will run on an iTouch, but it is obviously very, very different to the screenshots people have been posting from the later iPads and the iPhone 4S. It is not Retina resolution, all the textures are low detail and the effects are mostly cut out entirely. It looks something like an RPG on the Playstation 2 from several years ago. That being said, it runs at a reasonable framerate, occasionally glitching slightly or briefly freezing. It is still perfectly playable. Sound is fine, animation is fine, art design is still obviously good. The only outright ugly portions of the game are the 2D story cutscenes, where the textures are at such a low resolution it's not even clear sometimes what's going on - but even then the text and voiceover explains things fine.
There is currently a bug which stops iTouches - some, maybe all, I'm not sure - from going any further than the first mission from the hub world. The level will sometimes load, but it will crash inside a few seconds. (At least, this happened to me every single time I tried.) Phosphor's patch which should be out very soon supposedly fixes this bug and allows iTouches to play the game. It still looks very, very different to the screenshots people have been posting, and as far as I can tell the developers do not want to officially say that the game is supported on iTouches - even after the patch - because people will expect it to look exactly the same as the iPad 3 or iPhone 4S and then get angry with Phosphor when they realise it doesn't.
Would I recommend people play it on iTouches as it stands (assuming you can complete the game after the patch hits)? That's a tough one. Based on what little I did get to play before the bug hit I'd say only if you're prepared to make some big compromises. But if the rest of the game is anything like the opening it is still playable and it is still fairly impressive, even with so much detail unable to be displayed. Just got to wait and see, I suppose.