Liquid Glass
My opinion is rather anticlimactic: it’s fine. Techinically impressive, but the novelty wears off quickly and then it’s just there. Some users complained. I fully believe that the marketing department came up with this design. This isn’t about clarity, usability or speed. It’s about showing off. Sorry for the cynical take.
Overall, it’s an okay design, but there are three things I genuinely dislike:
Custom Icons
I don’t like the custom home screen icons. I don’t use it, so it is harmless, still I think it makes everything look the same.
iPhone First
The new design was primarly made for iPhones, the Mac is just another afterthought. I don’t have any proof for this, apart from community sentiment since 2007.
New Sidebar
This one really bothers me. Below is a quick mock-up I made to explain:

There are two screenshots of my app with liquid glass: one using the built-in NavigationSplitView and one with my custom version. I won’t ship my own, though, sticking with Apple’s frameworks is usually the safer bet.
The problem is the border around the sidebar. I understand why it’s there: it highlights the glass effects with horizontal scrolling content, by adding more boundaries. But the result is distracting. It takes up more space and creates the illusion that the sidebar is free floating as if you could move it around. You can’t.
I suspect Apple will drop the border eventually. For now, it feels like another case of “let’s show off the effect,” rather than a design that actually improves the experience.