Yeah, if you do that - then scale the sprite by power of 2 sizes, like SetSpriteSize(spr,128,128) will make the sprite 4 times bigger, but without blurring. It might be an idea to allow for borders, or somehow extend the game screen for wider devices. Like, the iPad2 has a resolution of 768x1024, iPad3 is double that, so if you use the same screen aspect, you'll have over 200 pixels leftover vertically - of course you'll still see them, but what would concern me is that the nice pixelated scaling will go to hell because it'll have an irregular screen size.
Just thinking that you might get better results if you take control of the borders yourself, like try and get the actual game area to be dynamic - maybe use the left and right sides for health/time meters on iPad's if you can, and use the top and bottom borders on iPhone5 etc.
So really, the game area might be 640x1024 - which is good because your pixel art will scale correctly. Then on 640x1136 screens, you'd use the 112 vertical pixels for the score (or whatever), then on 768x1024 displays, you use the 128 horizontal pixels for the score etc. It's definitely worth considering this stuff now, rather than later - Apple users are a nightmare for complaining about compatibility, and it really doesn't take much to set them off. It might sound like a pain to make your own borders, but I don't know, it might be straightforward to have a vertical and horizontal status display, in which case you have the ideal setup for properly supporting all the different resolutions.
We are making a dungeon game that uses mostly 32x32 sprites, it's a good look
I got a fever, and the only prescription, is more memes.