It looks like most people regard this as Randy's Magnum Opus. This was certainly fantastic. The funniest part was when he hit the screen. The transition effects are amazing. I remember looking at this trivia article he wrote talking more about it. I certainly wasn't expecting that ending.
Well, it'll make more sense later. You really get to see the Mario series depicted as something epic. It really is like a great fanfic. It's great to see all the characters contributing to the battle. There's just so much going on and such fine detail in everything.