I simply have never seen a Flash game this amazing. It just blows my mind that this was non-profit. I bow for you, my friend, as this is the excellent result of more than 3 years of hard work, probably. You should really show this to Nintendo, they would be amazed and let you work at Nintendo. I hope you can.
Anyway, onto the game. The gameplay and sound were true to the Mario franchise, the controls were perfect, the levels gave me fond memories of SM64. Really, it makes your older Mario game look like crap, no offense. There was humor, too, like that Toad in the tutorial that couldn't jump because you (Runouw) didn't program him to be able to. XD. And the secrets were pretty awesome too.
Overall, you're obviously getting a 10/10 and 5/5 because this game is the most awesomely awesome Mario Flash game ever invented in the history of mankind and the universe. Yeah, really.