Well I played through the true ending again and beat the final boss a second time (it was easy since I had the bouquet). I think that, apart from the annoying platforming bonuses which I don't feel like ever trying, I've probably explored at least 95% of what the game has in terms of content. I might play it again someday (but not any time soon, as even the mandatory platforming sections piss me off).
But overall I give it an A-. My biggest complaint (besides the platforming) is that my favorite website, YTMND, was only mentioned once... I wanted to visit it! Maybe there could be a special YTMND bonus episode? (YTMND is actually still around... well, it's glitched as of the last few days, but Max will fix it eventually, as he usually does)... I could even write the script for the YTMND adventure, if you would actually let me (probably not going to happen, but I figured I'd offer anyway).