Genuine question, from a users perspective what are they?
The couple times I've used it, I ended up going back to xorg because it turned out something didn't work (intel integrated graphics) right. Its sorta become a habit now.
If all you want to do is download a "demo" terminal, and put it in a HiDPI display, and enable fractional scaling, to show it to your friends, then yes, this works.
If you want to get some work done on any app (a text editor, web browser, ...). Then its worse than Xorg at the moment.
To avoid all this right now it's possible to just pick 1x or 2x and tweak font sizes to get a good mid-step. For a single screen this always works, but it makes combining different ones harder.
The other one that people value a lot is HiDPI scaling done "well". Mixed fractional scaling in Xorg doesn't really work and it's finally possible to do it. Although there I actually think it's still a half step and Wayland made the wrong choice in how to implement it. It should have been done client side for more performance and less fuzzyness. There's a chance that will also be fixed in the future.
Other than these it's a bunch of small things that are more technical than user-visible. Security is much improved for example. Some performance gains can be had from avoiding copying buffers. Etc.