I watched this movie for the first time in decades, and just had a few observations/comments. Very impressed with the restoration work, especially the soundtrack - there no longer seemed to be the jarring segues into the "talkie" portions that I remembered; and the cleaned up visuals make for much easier viewing. I've always enjoyed Al Jolson's energy as a performer in this film, "Toot, Toot, Tootsie" being my favorite. Having watched more films from the 1920's since my first exposure to this movie, I feel the character is kind of a male counterpoint to the female jazz-baby flappers of the day, Joan Crawford in "Dancing Daughters" comes to mind.
Regarding the blackface; IMO there is very little in this film and only comes at the end. I do not view it as an offensive stereotype; I saw no shuffling, nor hear any dialect, except in the single word of "mammy". There are dozens of other blackface performances in films (Bing Crosby, Fred Astaire, Mickey & Judy, Irene Dunne) which I find harder to watch than this one. Is Jolson portraying a black man singing a sentimental tune to his mammy any more offensive than watching Ruby Keeler cavorting around singing in pidgen english in the "Shanghai Lil" number in Footlight Parade?