SaucerScreen separation complete. Besides sealing the display to the glass, there aren't any major changes—the Mini 4 sports the same 2048 x 1536 pixels (326 ppi) as its predecessor.
Last year's update to the Mini series brought a single new feature, as a bit of a teaser of what was to come today: Touch ID. As such, not much there has changed, and the bracket and assembly look about the same as in the iPad Mini 3.
The other new feature on the Mini 3 was dual blobs of hot glue to hold the button assembly down. That particular repair-hampering detail returns as well.