I've got mixed opinions. I still hate the use of serif fonts either way; just something else for me to override client-side with user-CSS via Stylish. Say it with me people, serif is for print, sans is for screen. Screens (or at least normal screens normal people have) lack the dpi to clearly render serifs. PERIOD. Do not pass go, do not collect $100. They compromise legibility!
The new layout has some severe issues for large font/non-standard DPI users since the content column is declared in pixels but the fonts in EM. -- making it painfully narrow. If you're going to use EM to make it scaling friendly and meet at least SOME WCAG minimums, USE IT!!! EM fonts inside a PX container? /FAIL/
But then I HATE narrow content columns like how facepuke pisses on their pages.
The fixed sidebar is more annoyance than help, though perhaps a toggle to show/hide it might be nice? In either case it is WAY too wide thanks to WAY too much side padding. Same can be said for the right column.
The overall "left alignment" of the design is kind of wonky. Feels "incomplete" on a 2560 display even for a user like myself who puts the taskbar on the left and the tabs (Vivaldi user) on the right.
The editor is broken trash, but then given this uses some bizzaroland markdown-like that just pisses me off when trying to post things like CODE -- I still end up screaming at the display "Oh for f* sake, just let us use BBCode!"
Of course the not quite white text on the bright green for the buttons fails to meet accessibility minimums the same way the garbage white on light blue did on the old ones, meaning at least half the population likely can't even see what the submit button even says. Colour contrast, LEARN ABOUT IT! Also consider AAA small the minimum if using thin-glyph fonts since modern font-smoothing is NOT accounted for by the WCAG 2.0 spec. (often helps to test render instead of declaration)
Or if you're feeling lazy, use an online tool like webaim's to make sure you're not telling large swaths of users to sod off.
webaim.org/resources/contrastchecker
Which if you test, white foreground over #2FC681 is /FAIL/ even on the highly permissive AA Large. Hell, the devil grey #666666 text over #E8EAF5 fails AAA normal, not good when much of the thin-glyph and lineart is being done in it, after sub-pixel hinting ending up as bright as #888888's level (though coloured) -- an instant /fail/ even at AA Large.
Don't even get me STARTED about the ridiculous bandwidth and processing overhead. Even just a view source of the markup screams "WTF" with static images in the markup pissing on caching models. Yes, I know they're SVG, yes I know you're flipping the bird at accessibility by AJAXing in content out of the "pageloads are evil" paranoia, that's no excuse.
Given what this site DOES, I'd not be surprised if at least half the code client-side could be pitched in the trash with minimal impact on functionality.
Mind you, MOST of the above complaints are nothing new.