As you already know, GNOME 40 will introduce a new Activities Overview design that promises better overview spatial organization, improved touchpad navigation using gestures, more engaging app browsing and launching, as well as better boot performance.
But the GNOME 40 beta release is packed with many other goodies, including the ability to switch workspaces with Super+scroll on Wayland, the implementation of a Welcome dialog after major updates, improved fingerprint login support, better handling of a large number of window previews, on-screen keyboard improvements, support for handling monitor changes during screencasts, as well as integration of the clipboard with remote desktop sessions.