First a bit of background: Telltale's series prior to ToMI exhibited noticeable voice quality problems and the problem reached its peak with the second episode of ToMI, when enough people complained that Telltale released a new version with much improved voice quality. Fortunately that improved quality was upheld for the rest of the season, and I also noticed no significant problems with Sam & Max Season 3.
However for the first episode of BttF the problem is back. There is significant overcompression and/or distortion that is most (but not only) evident on the letter "s", especially when spoken by female characters. Obviously this isn't a complete showstopper but it is very annoying, and at least for me it has a significant impact on my enjoyment of the game.
To get this out of the way, this is not a problem with my computer or speakers. All other games sound crystal clear, and this is the same setup that I used to play the original ToMI Episode 2 (poor voice quality) and the rereleased version (good voice quality).
It's optimistic to hope that enough people will care about this issue that we'll also see this episode fixed and rereleased, but this thread is here in that hope :)