I played the older demo a while back and have also dropped my criticisms on that one, so I'll do the same here.
Compared to last time, the physics are definitely improved from last time. Jumping is a lot less momentum heavy, and the wall jumping is no longer as commital as before. They're still a bit rough, though: jumping has you go up pretty slowly, but then go down like a stack of rocks; and then wall jumping has you cling on on the wall and won't let go unless you manually get off it via jumping or pressing down (i think, i might've misremembered), which is not awful, per se, just very unusual.
Shooting has been improved as well, now the character can properly rapid fire like it would in Mega Man, though the bullets move pretty slow and take a while to vanish off-screen, making it still annoying to rapid fir, but at least to a manageable degree. The new (?) charge shot, however, is quite awful.
For one, it takes a while to fully charge up, which wouldn't be a problem if you could fire a shot when not fully charged, but you can't. You don't get a semi-charged shot, not even a normal uncharged pellet, just nothing comes out, which is massively annoying, since often I have nothing come out when I release the moment the enemy decides to make itself vulnerable because my buster was a fraction of a second away from fully charging. On the flipside, I also obliterated the miniboss with like, three charged shots, so maybe look into balancing that as well.
And then there's the new dash. You can't dash jump, so I barely used it.
Overall, quite a let down. In the 8 months that passed since that original demo, the game improved very little, graphically and mechanically, and still has jank, and the level design in this demo is much less interesting than the previous one.