The MadVR renderer is great. Video looks crisper and clearer, and it makes terrific use of the graphics card you're using. However, there are a few issues which I have with this particular renderer. First and foremost, when I use it, it is somewhat slow when seeking through most media files. When switching to a different renderer, I no longer have this problem. So the seek function should definitely be improved and fixed in future releases.
In addition, I'm disappointed there is NO 64-bit version of the renderer available right now. Hopefully the developer is planning to take care of this soon, as I do not intend on further using 32-bit media players on a 64-bit version of Windows.
Otherwise, it's a great piece of software and I definitely recommend trying it out.