I like how easy it was to use, as well has its flexible design for customization options (which you can only do if your proficient in HTML/CSS).
It's free! And so far we've been happy using this software over other paid ones out there - which are way more expensive than what our church budget allows us too spend at once time or project-wise anyways :P We have used many different media players but none compare when compared against all features offered by OpeNLp; ease of setup & deployment across platforms without having people learning complex code languages such as Java Script etc.; ability to customize themes / skins from within program itself via CSS stylesheet file uploads.