The core design of Dropbox Paper and the main Dropbox product didn't actually change much at all during this redesign (thank god). It would probably be more accurate to call this a rebranding, since most of the changes were to logos, marketing pages, and other content outside of the core product.
I've always loved the crisp, clean blue and white aesthetic of the core Dropbox (and Dropbox Paper) UI, and I'm glad they haven't made many changes there. But I think the rebranding is an absolute disaster.
I don't mind the changes to the shape of the logo, but the new color schemes are just vomit. I agree with @bstrong that it seems like a cry for attention. I also agree with his critique of Sharp Grotesk.
It does look like Dropbox has recently pulled back a bit on the rebranding. When I checked out their marketing pages after the initial rebranding announcement a few weeks ago the new vomit color scheme was all over the place, but now those pages are mostly back to the far less ugly blue and white aesthetic. Maybe they're listening?