We had this discussion about 6 years ago, I forget the thread title, maybe Necro will remember it.
Anyway, Yes the Ninja Giaden Hu-Card does leave something to be desired and most of the complaints are in the sound realm and the lack of good scrolling - seen specifically at the beginning of game where the background is jarring along in a jagged fashion as you repeatedly slash at re-spawning enemies while trying not to fall into the abyss. It has some serious flaws compared to the NES version, and most people back when were really disappointed in it for the value... Even in 2010 it was one of the more expensive games and after shelling out $65-70 for the game when NG1 was still about $15 for the NES in some cases they just went and played the NES version.
Anyway, the chiptunes are "good" but kind of suck compared to the NES music, and are like a more minimalist version, which I assume is due to space limitation.
A few other things, Ryu is really clunky. The control responses are not as precise as the NES version, and the speed at which he slashes his sword is significantly slowed down compared to the NES, which has caused folks who have memorized the playthrough or like to do TAS speedruns immensely frustrated because it DOES NOT APPLY HUMAIN. Also, you will inevitably take more hits as a result of this, and it makes Ryu respond more like Moon from Ninja Spirit (Who is the slowest platformer protagonist I can think of) and you will just incur a lot more damage. It makes the game harder as a result imo. f*ck. I want to play the NES version now.
So there you have it in a nutshell.
Oh the color palette is a lot brighter on the PCE version, and the sprites are bigger, but I don't think that constitutes for better gameplay. Nice looking game, not so fun to play. But still pretty badass.