More details and LCD shots to follow later but the anti skew works well as long as the background is plain, here's an example below...
Left is the original shot and right is the resulting auto correction image. During the process there seems to be a choice of tight or loose framing but I have to test that further later. The R5 and R6 are a little smarter and allow choice of 5 framing differences, to either select tight or loose framing, or framing of other rectangles in the image. For best resolution, take the picture normally and then choose deskew in the replay menu, because in the R5 at least, the Scene Mode of Deskew puts the camera back at a low 1.2 megapixel resolution.