I think most of that gameplay stuff sounds fun, personally. Inventory system might not be necessary, but other than that I'd at least be interested to see how most of his ideas worked in a game.
All in all I liked the video. But criticism where it's due - I'm gonna tear apart that redesign. In detail.
First off, let's remind ourselves why Sonic became a beloved design in the first place.
Cute. Simple. Iconic. The perfect blend of a few bright colors, a lovable compact figure, and a very unique hairstyle, all strung together in a pose full of personality.
Now let's take a look at this redesign.
All over the place.
First let's get the glaring issue out of the way, the legs. Sonic's head and upper body here are obviously going for an adorable toy-like appearance, something I could picture on a small teddy bear. But then the legs are ridiculously long lanky sticks, maybe even longer than his Boom design. The top half is trying to be cute, but the bottom half gets it wrong because lanky isn't cute. it also has no style or grace. This is more of a personal observation on my part, and long, thin characters can be appealing, but for the most part, the most iconic cartoon characters are shorter, or otherwise more compact. Mickey Mouse has thin limbs, but still has a fairly normal physique that keeps him short. Mario is pudgy with thicker limbs and lots of curved lines. Pikachu, Spongebob, the Powerpuff Girls, Hello Kitty, they all had very broad appeal, because in totally broad terms, smaller is cuter.
Speaking of Hello Kitty, that's the first thing that comes to mind when looking at Sonic's face here.
One of the cutest and most marketable faces ever right there. When the term "iconic" is thrown around in regards to character design, this is usually the first character that comes to my mind. Dot eyes, little nose, no mouth, blank expression that can be put pretty much anywhere and still look cute no matter what. No real personality, but it's just a cute design that is completely sweet, charming, and inoffensive.
That ain't Sonic.
While I do think Sonic should be cute, and I don't think his personality should be overplayed, he is NOT a blank slate. In the Genesis classics, he always had a look of focus and determination, which turned into angry impatience when left idle for too long. Even without dialogue you can tell what his personality was like. Bold, hungry for action, but at the end of the day, still a charming good guy. Making his eyes plain dots with no brows or expression is about as far as you can get from that.
Lastly, the colors. Removing the big eyes and gloves removes almost all of the white from his design, aside from his shoe straps. Blue, red, white, and peach-ish skin color are the four main colors of his design, and they all work very well together. The red is the loudest color of the four, so keeping it restricted to only his feet is a good way to have them stand out. The blue takes up most of the body, and the peach and white work together to keep the blue from overpowering the others. Without the white of the eyes and gloves, there's TOO much blue, on top of the blue arms, which we're all pretty sick of talking about I'm sure. The original design struck a perfect color balance, but now it leans too heavily in one color's favor.
I probably went into unnecessary detail here, but hey, sometimes I think unnecessary detail is...well, necessary. The original design got a lot right, and I feel it's still a relevant character design to this very day. This proposed redesign has good intentions, but there's no way it would be a welcome change.