Believe it or not, it actually looks pretty good throughout. I don't know what magic is used, but I have plenty of 720p and 1080p MKVs (that are 4.5 to 8gb in size respectively) that, despite having bit rates that are 1/2 to 1/4 that of the original blu-rays, the PQ is near identical.

Granted, there may be compression artifacts that I am not noticing, but I am watching these on a 65" Toshiba DLP HDTV, so the screensize is big enough that any artifacts should be quite visible. Also keep in mind that said MKV programs are strickly movie only; no menus, chapter stops, extras, etc. (though some do contain subtitle tracks, alternate audio tracks [such as dubs] and even commentaries)

And to confirm it is 720p (which I prefer, as the straight 10 to 12gb 1080i HDTV MKVs have interlacing issues; the 720p versions look just as good and also eliminate the "combing" from the interlacing).