As for the production values, it turns out
that after the location/filmed parts of the production were completed, the union that operated the video cameras in the studio went on strike for more pay, so they had to complete the whole thing on 16mm film (since those cameramen were in a different union). The people who assembled sets were also
on strike, so the whole thing had to be shot on location. I can't find any indication that the sound recordists were on strike too, so I suppose the technology at the time just didn't enable very good audio on location, or at least on the locations they had available to pass as UNIT HQ. (And it turns out they really did shoot at Madame Tussaud's.)
But because this was the only DW installment (other than the '96 movie) to be shot entirely on film, it's ironically the only classic story suitable to be released on Blu-Ray.