I have Windows 8.1, and Blu Ray playback is working fine, but I did a clean install.
Sometimes when watching movies with external subtitles, the subtitles stops working. I got some weird issues with subtitles and 3d movies (sometimes the subtitles line breaks make half of the subtitle go to one eye, and half to another...).
For that, I'm using media player classic + 3d subtititler, and put the tv in 3d mode side by side.
I have also issues with trutheather surround over hdmi, as stated on another posts.
For blu-ray playback, I have no issues so far.