The updated graphics in Cavestory+ look nice, but the updated soundtrack saps all the energy out of it
Luckily you can choose which you prefer from either of those so it's not an issue, I just think it defaults to the new version of the soundtrack when you start it but you can change that in the settings (trust me it sounds way better).
Also Cavestory+ gets seasonal patches that can be fun
I've only played most of the original downloaded through the fan site and with the English patch. Didn't know you could switch between original and remastered sounds and sprites in + so that's neat. Just depends if you want to support Pixel financially or not I guess...