Does what it says on the tin.
Compare these two crops, one with the standard iPhone camera app and one from 645Pro.
Same cat (mine), same bed (mine*), same pillow (mine*), same iPhone (mine).
It's pretty clear that the app works isn't it?
Leave aside the styling for a moment, with the different capture aspect ratios 6x17, 6x9, 645, 6x7, 6x6 as film backs. Don't look a the film modes, K14, FC5, E6K, C42, T3, H5, F4. Don't consider the live histogram, and AE and AF lock.
Just concentrate on the way it saves minimally compressed JPG files or a lossless compressed .TIFF file.
That is for me the real killer feature, getting closer to the best quality available from the sensor. It's not RAW because Apple doesn't let you get that close to the hardware, but the quality improvement is fantastic.
And the response to my comments on the application in v1.0 ?
All the features I asked for (and more) are in the next version.
9/10 for this app, probably 10/10 for the next version ... 645 PRO for iPhone, for ultimate camera control and image quality
P.S. after consulting the cat, (*) the bed and pillow are hers.