As you may already know, there was a Registry tweak which could restore the classic UAC prompt. In the upcoming Windows 10 Creators Update, it was eliminated, so only the modern touch friendly dialog is left in the operating system.
With Windows 10 Anniversary Update, Microsoft has updated the appearance of the UAC prompt. The refined dialog looks more like a dialog from a Universal (Metro) app and fits the overall flat appearance of the operating system. However if you face issues with this new UAC prompt, here is a simple trick to disable the new dialog and get the old Windows 7-like appearance back.