After reading the linked page, it appears that at least some of the security issues are addressed:

Applications will be isolated from each other by default and can only interact with other applications either through a GUI prompt asking for permission, such as with screen recorders, where it will only be allowed to record the window specified or by explicitly giving the application permission before launched (such as a window manager or external compositor).

I'll probably continue to push forward with Wayland, but I suppose I'm pleased that someone is taking a crack at trying to improve X11. The author also mentions potentially using this as a lightweight and safe replacement for xwayland.

That's what X is known for right?