Halfway through World 2 right now. I'm having a blast with this game. It's been entirely TOO long since the last 2-D Mario platformer.
Snapple, I was a bit concerned at first too, but then I figured that once you beat the game once, you might be able to save at any time. It would kind of be silly of Nintendo not to include a save feature to save your collectables if they expect you to backtrack through the levels later on.