I can only say how an amazing job you have done!
Still, brands aside, gameplay is something you should take special care about...
No player wants a "too speedy" game that they feel like is making them catch up with the gameplay...
You put all your efforts in making your engine as fast as possible, but your gameplay is way to abrupt... It needs smoothing... You character accelerates almost instantly... And sometimes you even jump off screen!
So my advice for you is, slow a bit the scrolling, the jumping and all the visual artifacts... Put most of your efforts in the character, making it unique and LOVABLE, that's Mario main advantage... And put your game in the hands of a few kids (15 to 18 yo)...
Listen to them... Usually, they will be right...
Oh, and if I were a gambling man, I wouldn't dare betting against you!