The ease of use, ability to customize for each department's needs (or even one-on-one), flexibility in implementation - there are so many features that can be used depending upon your organization size/structure! I wish we had more reporting options available because some departments do not like using Excel for data entry purposes; however with PowerBI you have access to almost every report type imaginable including pivot tables which is very useful when entering information into an excel spreadsheet format.
There was nothing really bad about this product as far as functionality goes but it would probably help if they released versions sooner rather than later after initial release. We needed something easy to implement yet customizable enough where users could create reports within minutes or hours instead of weeks sometimes months. It has allowed us to see exactly how our employees spend time throughout all areas of our organizations.