Ahhh SMB2NA, i remember everyone asking why it was so different, i was the only one with the answer in my neighborhood thanks to a chinese friend who actually had Doki Doki Panic and SMB2J and i played them in his house before the SMB2NA launch...
I like SMB2J because is a really good challenge, that being said, I think SMB2NA is a better game than SMB2J in terms of being on the Super Mario series, and in Japan (when it was launched as Super Mario USA and remade in the All-Stars and in the SM Advance series) they really liked the game, beacuse of that you see elements of the game in World, 64, Yoshi's Island, RPG, New SMB, Advance Series, even in The Legend of Zelda... And personally, the Ninjis are one of my favorite characters on the Super Mario series...
BTW, Shigeru Miyamoto was the creator and Koji Kondo composed the music, what else do you want? 
