Select up to 12 images when you're in any view and open Survey mode to see them all at once.
To open Survey mode, click on the icon as shown in the screenshot below or hit (N) to open and (esc) to dismiss.
By default it will enter the image compare view
To compare faces from up to 6 images at once, select multiple images and open up Survey mode and click on the face icon as shown below.
To view this mode directly, click on the face icon or use (Shift + N) and (esc) to dismiss it.
To remove any images from the survey mode, click on the icon as shown below or press (,)