The tool was created for more advanced users who will appreciate the available functionalities, but it will not work very well in the form of a typical media player, being at least an alternative to Windows Media Player. Not everyone needs an application that offers support for OpenEXR, PSD, MIFF, TIFF and EDL formats, passive sound in 3D or a program dealing with HDRI content support, i.e. what mrViewer can provide.
mrViewer is characterized by a dark, rather complicated interface, which will take some time to master even more experienced people. Especially that you can get the impression that not all options have been arranged in a logical way (in fact, each of them is available at your fingertips from the context menu when you right-click).