Singin' in the Rain is one of my favorite films, though I am not a fan of musicals. It is not only a celebration of singing, dancing, Gene Kelly, and vaudeville antics, it is a celebration of the medium of film. Though it was made at a time when Hollywood was famous for its rigid and creativity-stifling production practices, Singin' in the Rain is remembered as a landmark of innovation and style.
Despite this being both one of the greatest and one of the most popular films of all time, MGM (and now Warner) has released it as a sub-par dvd. It lacks any real special features (except for the trailer), though I imagine there are a number of documentaries and perhaps interviews about the film, and certainly many qualified film historians that would have been willing to record a commentary track.
The image quality is lacking. This is the worst-looking dvd that I own from a major studio (Warner hasn't remastered for the rerelease). It is exceptionally soft, and digital artifacting abounds. The colors are off, and the print could certainly be cleaned up. It was probably duped from a laserdisc. This film would truly benefit from a restoration and re-release (like some of Hitchcock's films have gotten).
If you love the movie, by all means buy the disc, but if you own the VHS or Laserdisc copy (that isn't all worn out), I'd hold out for a special edition, because the dvd won't look any better than a laserdisc, and not that much better than VHS. What a fantastic film.