Gnome 3 was a big departure from what users were used to in Gnome 2. In Gnome 2 you could configure panels by simply dragging and dropping elements. In Gnome 3, this customization is achieved by installing extensions or Gnome shell themes. Installing extensions can be easy, but it will never be as easy as dragging and dropping elements with your mouse.
For many years, when you used XFCE and then went back to Gnome 3, you could perceive how much slower Gnome 3 was. Now, performance has gotten much better to the point Gnome 3 is my default desktop again.
You can tell there are users are still disgusted with the Gnome 3 UI. That's why the MATE and Cinnamon projects exist.
Any gnome extension I've installed I came to regret it without exception (on Ubuntu). They always ended up breaking something in a fatal way where even after uninstalling them would leave the damage. For example now my windows won't snap to half the screen edges (to take up half the screen) any more, just randomly. That's just one example. Extensions have always caused me headache and mess.
People often claim Linx desktops are "there" today, but the lack of polish and glitches are still painful. Not horrible, but not comparable to Windows or Mac. It's surely solid enough to use as the main daily OS, but you really have to stick to the defaults as customization often breaks stuff.
On Mac I can't tile windows without installing a third party app, on gnome I can. On windows three finger swiping between desktops when the task view is open is horrible, but gnome handles it perfectly.
I use gnome, mac, and windows daily. They all have pros and cons, but I can't see how anyone could claim Windows or Mac are well ahead of gnome.
For many years, when you used XFCE and then went back to Gnome 3, you could perceive how much slower Gnome 3 was. Now, performance has gotten much better to the point Gnome 3 is my default desktop again.
You can tell there are users are still disgusted with the Gnome 3 UI. That's why the MATE and Cinnamon projects exist.