I saw a demo of it on the European SharePoint Conference in Copenhagen in 2018. Sebastian Fouillade, who showed this, compared this big change with brain surgery. All the urls, all the connections. But now it is possible. Today I have seen it even in my standard release tenant.
It is really appreciated. Soon it will be possible to rename misspelled sites, like “devlepment” to “development” etc.
I also can image, it will be very handy to change the url of a SharePoint site that was automatically created for a Team (through the Office 365 Group). The team might have some longer name, but a simpler url is often appreciated.
I have tried and seen that also the automatic redirects from an old site url to a new site url works.
Caveats and Limitations
mailNickname ≠ site url
Now it is even more important to not to rely on the fact that mailNickname of an Office 365 Group and Site url are the same. As Elio Struyf describes, it is not a good idea to compose a URL from the group name. I have used in PoCs the site url to get the group id: