*drools over the Tetris gameplay section.*
The fact how the emulator guesses the geometry of different aspects is just amazing. How it determines the thicknesses of stuff is superb. Just look at the blocks compared to the surrounding "brick" frame in Tetris/Hatris, and the windows in Chip'n Dale's backgrounds. When I looked at the apples in Chip'n Dale I was like

and the player characters in both platformers looked very good too, just like
nanoblock models. The logo and opening screens of Hatris looked pretty bad, but the cute little heads and hats in-game pretty much made up for this.
One more thing. About the shadows, they're really nice. Sprites casting shadows on the ground looked really cool. But how customisable are the shadows(I haven't even tried the web version yet; sorry about that)? Can we tune them down or change the position of the light source ourselves, instead of disabling them completely? They sometimes obscured important stuff that made the games much harder to play. For example, in Tetris, the blocks in the left columns were being hidden by the shadows and the shadows sometimes made text(such as scores) hard to read too.
I think while turning a game 3-D wouldn't make much different to game mechanics or make games easier to play(actually this most probably makes games harder to play), it'd be quite awesome to use 3-D mode to playback game recordings (such as TAS recordings) originally done in the normal mode.