Sounds great - just what I wanted, as presently all I can do is review my shots as soon as they are taken and I have to have the typical 1meter long Apple lightning cable!
Sorry to be thick but, when you refer to "taking full advantage of the retina screen "
Does it do that now? Ie can you see it in 2048 x 1536 pixels and pinch-outwards to expand? For both the photos you have taken and the live view image?
It's an iPhone app, it will run on the iPad, but it's designed for the iPhone screen.