I had no problem with the sound quality of the 5.1 mix, which I found excellent in all regards. Even better, and unlike some discs I have, there is no brittle digital sound, excessive high end, or harshness that I can discern; in all, a wonderful mix for a damned good album. I'll get into more detail the more I listen, of course.
Only debit of this package is the lack of surround for the 45 versions (there are four). Aside from that, nothing negative for this listener. This is easily a '10' in all respects.
Having three key Buckingham/Nicks Mac albums in surround is a delight, and I wish that more acts would do the same. Although, yes, they are pricey, they are also well worth the investment, IMO.
ED