I have to say this is one of my favorite movies, and is considered by many to be one of the greatest films of all time!
First I'll just get the anachronisms and such out of the way. The film opens with a premiere at Grauman's Chinese Theater in Hollywood in early what I guestimate to be February of 1927. The problem is, Grauman's didn't open until May of 1927. In terms of costumes, it is rather amusing to see bobby-soxers running around Roaring Twenties Hollywood. These - among others - are really just technical things that only bother me, but as you know I must mention them. Moving on...
A good example of a jukebox musical, this was probably the "Moulin Rouge" of its time. It took songs from old black-and-white musicals of the 20's and 30's and did a wonderful job of entwining it throughout the plot. The numbers are well balanced, but small children may lose interest during parts of the "Broadway Melody Ballet" toward the end of the film.
Kelly and Reynolds share great chemistry on screen, despite problems teaching her how to dance (she had trained mostly in gymnastics). O'Connor brings slapstick and sarcasm, but I have to say my favorite actor in this film is Jean Hagen as Lina Lamont. It takes a lot of talent to pretend to be bad well, and she goes all the way. Lina is just one of those characters you love to hate, and her oblivious musings make for some of the most charming humor throughout the movie.
Needless to say the dancing is phenomenal.
This is the ultimate feel-good movie. You can't go wrong with "Singin' In The Rain"