Super Mario Bros. 2 is a disgrace to the other Mario games of the NES era. Still, it is a solid game.
This game, for all it's worth, has amazing graphics for an NES game. Everything in it looks great. The sprites are a drastic improvement over SMB1. The night and day effects are a nice touch, too.
Not everything is good though. The way you defeat an enemy is not in Mario canon. Jumping on an enemy will not defeat them and that takes a lot out of what makes Mario... well... Mario. You must actually pick up the enemy and throw them. Does not sound like Mario to you, am I right?
The sound is pretty good, though. The first stages theme is still to this day a pretty memorable one, and let's not forget that with the American SMB2 we now have Birdo in the series, who is still pretty well known.
Overall, this game is not the true SMB2 and it will never be the true SMB2, but it's an okay game to play in between sessions of Super Mario 1 & 3.