The basic app allows you to take pictures of documents, crop, and organize them.
The Pro version has an online OCR engine to recognize text from scans.
A feature not seen in many other apps is the ability to take a picture of two pages of an open book. This particular feature was recently updated to allow faster processing.
So, if you want a quick way to scan in pages, consider the free version. If you want the more powerful OCR engine that will allow recognition of text in multiple languages as well as editing, consider the Pro version.