I use it too. What I found really useful is the OCR feature. It automatically scan the document content and I can search it later via the web UI. Image document like ID card or the like is not really accurate as I found it missed major portion of text or the most important section (the ID number itself), but I can manually edit it if necessary.
It's also one of my main used apps. Love being able to search sanely instead of rummaging through papers. I hate scanning documents in though, that's time consuming.