Totally and bizarrely misbegotten efforts from Sony. They would have done fine if they'd just released the quad mixes - with a center channel created by summing the FL and FR channels if they really wanted to. Instead they upmixed the stereo channels into 5.1. The result is that in The Planets the organ which used to be in the surround channels of the quad mix is no longer present. And the Bartok, one of Columbia's most aggressive quad mixes (the cover shows the distribution of instruments in quad), it's just flat and artificial instead of being the experience of the orchestra surrounding you that was originally intended.
I've seen rumors that essentially all of the early Sony classical reissues from the analog era were upmixed instead of new proper surround mixes from original multitracks, but these are the ones where it's most obvious. Dutton has already released a number of discs closely related to these, including the Boulez/Stravinsky disc and the Bernstein Haydn disc - I'm hoping they get to these as well.