Well, this is a two-disc set which contains the original Shrek movie, but the review pack consists of just one disc, with the 14-minute animated Shrek 3-D presented in both 3-D and flat versions, with four sets of anaglyphic (red and blue) paper and celluloid glasses.
Almost all 3-D movies made so far have been done pretty much the same way, using the principal of polarised light invented by Dr. Edwin Land.
Under this system, films including The House of Wax, Kiss Me Kate, Dial M For Murder and Flesh for Frankenstein were filmed using parallel lenses simulating the parallelex difference of our own pair of eyes. Projection was done using two strips of film. One strip was viewed through a clear lens designed to allow vertical light through. The other strip was viewed through a lens allowing horizontal light through. The brain merged the two images into one, and a truly effective 3-D image was the result.
That's proper projected 3-D. And that, I believe, is the system used for Shrek 3-D in its theatre screenings.
That system can't work on television. So, for DVD, there is a single film image only, and a slight red tint is given to what was the right-eye's image, and a slight blue tint given to the left. The idea is that if we view with a red lens over the left eye and blue over the right, those layers will be largely eliminated, leaving two coherent images for the brain to resolve into 3-D. Got that? Work at it...
Well, it doesn't work too well. Anaglyph 3-D was used for some of the classic 3-D movies when it became too expensive to fit out cinemas with the proper projectors, and it didn't work in the cinemas either. About the only time anaglyphs did work was during the short boom (lasting about three weeks) in 3-D comics - Superman or Mighty Mouse in 3-D.
The story of Shrek 3-D is very slight, as can be expected in a movie running only slightly longer than ten minutes. Mrs. Shrek is abducted straight after the wedding. Shrek and Donkey rescue her, and they head off for their honeymoon.
It's really only an exercise in 3-D, and the 3-D is patchy in the extreme, with lots of double-images instead of 3-D even under optimal lighting conditions. There are some moments when the 3-D effects work well, but these are transitory. The slightest movement of head or the fragile glasses can instantly destroy the illusion.
The Shrek 3-D transfer is good enough quality; its problem is simply that anaglyphic treatment of a colour movie is a very dodgy proposition which distorts and darkens colours and is only partially successful in giving a decent 3-D effect. The problem with the two-dimensional version presented as a viewing alternative is that this story is really too slim to support 'flat' viewing; it relies on its 3-D gimmick as its whole reason of being.
The only extras on the 3-D disc are two separate widescreen anamorphic trailers for Shrek 2, presented in very impressive quality, along with two ads for amusement parks. I can't comment on the quality of the accompanying disc with the original Shrek movie on it, but it is assumed it's identical to the existing single-disc marketplace DVD.