In the past 4-5 months I've tried several Blue Ray DVD players; several models by Samsung, a Sony and as of late, this LG. I've had different issues with each of the previous units which is why I kept trying other ones. My Conclusion is that the LG is the best (from my stand point). It is the only one that played anything and everything I throw at it. It played all MKV files (even the one that a Sony unit complained was corrupted), it was able to recognize and display both subtitles embedded in the MKV as well as added subtitle files within the folder. It did so both from a disk and from a connected USB device. It even played DVDs that were encoded in PAL (!!!), something none of the others could.
So, I'm sticking with the LG BP620C.