see work passion here 
i like nice graphics.
since start, i had a lot problems with shadows(point light shadows mostly). so IMO shadows improvment would be nice.
why? would like to make a nice indoor lighting with shadows, current point/spot shadows have a lot issues. annoying one is for example overlaying of this shadows.
example topic:
that you already seen 
im not sure if this still exist, anyway i had problem with shadows with multiple lights.
there are more problems, like flickering, where need special paramaters to avoid it, and more.
so i always hoped someone will upgrade this shadow system.