Great app. However, a comment about your description - 'free.' I spent 20 minutes trying everything I could to use the Palette view and only by chance discovered that it was a for-pay option.
You might want to edit the callout on your first picture on your site ("Simplified palette view - optional extra" or some such). Also, though I have no idea how hard this is, maybe have Palette greyed out on the selection menu until the user purchases the option.
Your app is so well done and should be hugely useful, but, since I really wanted Palette View most of all, part of me ends up feeling as though calling the app "free" was just a come-on. I'm sure you don't mean it that way, and $3 is a tiny amount for such usefulness, but... anyway, I'm hoping I'm not upsetting you in any way. I just think there might be a better distinction between what's free and what's available only by upgrading.