The early (1956-1959) RGV recordings sound the best. They are far from perfect or spatially natural, but really charming for fans of the music. The tonality of the instruments was better then, and the sound was full and lively. The piano always sounds like a small upright that is just barely in tune and burried in the corner, but I've grown to like its spooky sound. The cymbals, especially on some of the earlier Blue Notes, sound too "white" and splashy (e.g. Blue Train), but still exciting and engaging. The Prestige recordings usually sounded the best with less of the "white" cymbal sound.
As you get into the 1960s and RGV moved out of his parents house and into a studio, the recordings get thinner, brighter and generally worse sounding. This is not just true of RGV's recordings, but the jazz industry as a whole. Early transistors and changing recording techniques played a part in this.