I would like to chime in on the video stuttering with HD content (when buffer is full) issue, post 4.2.
From the material I have tested, it appears the issue has been fixed for me.
This is only a short term assessment as I have only had time to test 2 sets of source material that were giving me trouble prior to applying the 4.2 update.
Also, the subtitle issue on 720p material appears to have been fixed as well.