I would like to start by saying this is an amazing app, better than all the others RAW photo editor apps in the store. Besides its professional functionalities it has a minimalist look and feel that makes everything even better.
But after using it to edit many photos Ive been taking, I would like to make a few suggestions:
1) Add a grid while cropping. Something similar to the straighten grid;
2) A comparison to original button is very important, not only the comparison the app already have within the edition youre making. Sometimes, when Im in doubt if like it or not the changes I made, I have to go back everything and bring the RAW photo again, losing all edits I previously made;
3) Undo button as well very important. I know you have the History functionality but its not as fast;
4) BTW, History cannot go back 100%, which brings the need of a nice feature such as revert to original. Currently you can achieve this by importing the RAW photo again;
5) It would be nice to have the histogram while making some edits, such as brightness, contrast, shadow, highlights, contrast, etc.
6) When using curves and luminance the graphic could already come with a point in the middle of the chart, leaving it up to the user to decide to move it or leave it in the center and adding other points above or below it.
7) And the most important: batch edit. When youre working with a big number of photos (say hundreds), its difficult to keep track of where you stopped, whats the next photo. Allowing us to import more than one photo at a time would bring the ability of displaying a little icon on the photo (or something similar) showing it has already been modified.
Well, these are my thoughts after heavily using your app for a month. Ill be traveling for a long time without a laptop, so Filterstorm its the perfect tool for me.
Again, its an extraordinary app and I love it. I just thought I might help somehow by giving an outside opinion.