The Saturn version has horrible slowdown. Also the sprites and backgrounds are pre-scaled in the worst way (pixel scaling - every few pixels there's a duplicate to make them wider - 240 to 320). There's no alpha transparency even. Everything that was transparent is 50% dithered. It's got new stuff but even the developers made an apology in text on the CD.
to quote an old babelfish translation in something like engrish:
As for Saturn development when it was unprecedented, to the place that
in connection with development period, the efficiency of hard is
pulled out, the fact that it is not possible is regret, but (even then
it inhaled and the ぶ it is was late (the tear)) as a degree of
transplantation we think whether tolerably is not.
You can try to read the full developers notes
here if you find the bad translation as endearing as I do (Google's transator would do better than babelfish did in 2002)
In short, the KCEN programmers struggled with the tight schedule and failed.
. I played SoTN on the PSP and I loved it. Never even bothered with the main game after I unlocked SoTN 
