If I reviewed apps on the App Store - I would give Photo Sort a 5-star rating. It works great in sorting my photos into folders. You can input any photo that's in the [default] Photo app. In addition, you can quickly create folders, whether on the main level or in as many sub-folder levels as you wish.
I now use it as my primary app for storing and viewing my photos. No, you cannot input photos directly into the Photo Sort app, but it is a very simple one-click option to put photos into the app. They are then duplicated - but I've had no qualms about removing the photos from the default Photo app once they are in the aftermarket app. All this without needing a computer or iTunes (well, for those new photos not already sync'd with iTunes).
So, yes, some apps get not-so-good reviews on the App Store. But, IMNSHO, given what you want to do, Photo Sort will work for you.
Of course, and as always, YMMV.
Marilyn