@sim This is an interesting and a long topic... and users generally prefer applications, which have similar style, visual elements and which behave similary i.e. which are predictable for the users.
And I like that e.g. Google promotes its "Material design" that is not only about colors and icons, but about application behavior also. No matter if this is a dialer, photo editor or a social network client: it should be familiar to a User right after the first launch...
?!