It's an excellent tool for managing our invoices within Salesforce as well as generating reports from them easily! The price point makes it accessible even without any technical expertise - I can have my team members work with this product intuitively while still being able to provide support when needed via their FAQs or through emailing helpdesk@fluixsoftwareincorporated.com if they're stuck at something specific.
There are some minor features (ease of use) which could be improved upon but nothing too major right now. We've been using Flux mainly because we were having issues getting out invoice data into sales force properly so had lots of manual processes going around copying/pasting info etc., however once those got sorted everything else has fallen away pretty quickly since then.