It's super slow to load.
It's slow to use (Scroll is sluggish. It loads giant images and puts huge autoplaying videos in your face. Comment function now starts an ugly html wysiwyg editor).
It misses features (outgoing links in the sidebars are gone).
It takes away screen estate by having a fixed element on top of the screen that stays there when you scroll down.
It's buggy (often weird overlaps between elements happen when you resize the screen).
It's confusing. When I click on a post I get a view that shows the post in an overlay of the page I was looking at. When I reload the page I suddenly get a completely different view with only the post.
It's almost unusable on my iPad (where I have to beg for the desktop version every time I open it because the mobile version is even worse).
It seems like they are still A/B testing it. Because sometimes I get the redesign and sometimes the original design.
Funny enough, I can see how the redesign might increase user engagement. The endless scroll with content right in your face is kind of addicting. It pulls you in a state of "I hate this. And I hate myself for using it. But I can't stop. I will just scroll down one post further.". So the experience is worse but the KPIs might be better. I bet this is how booking.com became the hell that it is.
I would love to see how the numbers of those tests look like.