My opinion on this hasn't really changed over the last 15 years. I just had another listen and really I think Blue in Green and Flamenco Sketches are the highlights as they have lots of feeling and some interesting turns of phrase at times. The rest though feels like filler, undemanding but sounding beautiful enough to make it ok for those who don't listen to much jazz and just want something that sounds nice.
As for best jazz album, why does there have to be a 'best'? Things can be good in different ways, it's just a marketing thing to say something is the 'best' out of everything. Kind of Blue does seem overrated however, but perhaps mainly by those who don't know much jazz.
An interesting article here:
Kind of Blue, Reloaded | Blue Music Group