Picked up my copy tonight. Started watching "Leaping Of the Shrew" and unfortunately discovered the dreaded "unable to read disc" on a small portion of the episode. I've had that problem on other Universal sets with double-sided discs before, so I'm not all that surprised.
I checked out a bunch of other episodes already and they all played fine. It's good to hear the "rock" version of the theme again too, despite the fact that I'm one of the few people here that like it better than the original God-awful theme!
As for the music, I watched "Nowhere To Run" and it seemed to have its music intact, although I can't tell if a song has been omitted in the very beginning of the episode as there's generic music in the background. Picture quality looks good, though I found "Killin' Time" to be a little on the dark side. No big deal, though. When I got back I realized I had the Season 5 coupon saved back from when I bought Season 4. I always forget to use those things every time!