To a layman none or almost none direct benefits. But there are non-direct benefits like those listed by sibling comments. However it will, in longer term, simplify work for developers, while in short term it will be or rather it is a complication in the transitional phase.

It is an evolutionary step for end users, there is no revolution really. What is the benefit to a layman of a program to change bogies in all trains? He doesn't care about regenerative breaking, so smoother ride? But until almost all of his rides are on this newer platform he would not see a real benefit. Then when it is finally there he will only see its absence. Same with Wayland.