I am still struggling to process that this is a real thing. It really just looks like a fan concept from five, ten years ago, and i mean that in the best possible way.
I think the new papery visual effects are done very tastefully to play off of the original's artstyle. Like, i love the skeleton-rigged character animation and how it makes the characters look layered and smoothly animated. Now you can see a sliver of an uncolored edge on each layer, a far more subdued way of presenting the characters as paper cutouts than slapping a bold white outline around them. Other effects like the reflective surfaces look great. I can't wait to see more assets uncompressed and in HD, and now i'm really curious what could be done with Super Paper Mario's artstyle in the off chance that's ever remastered.
I'm surprised they're adding big band elements to the music, but i'm cautiously optimistic. The first two games' soundtracks could really use some touching up. As long as enough of its character is left intact, it should be fine.
Also, it's so cool seeing all of the original character designs, and the photo of the Paper Mario 64 partners, again. The Super Mario Wiki was my introduction to these characters, so i think it's appropriate to gush about them all here.
I really hope that this and Super Mario RPG do well.