Some song and dance numbers are pretty good
Dancing Feet
is great - especially when it goes into the dance sequences. Reminds me of later work by Busby Berkeley. BTW that's Bing Crosby singing, in his first-ever movie appearance:

I don't know if Paul Whiteman gave himself that title, King of Jazz, or if someone was boasting for him. He fostered a lot of jazz talent but I think most of them were white, if not all. This is the first time I've seen Paul Whiteman. I thought it was Oliver Hardy at first.

He wasn't the king of Jazz though. There were far better musicians around at the time and they were black.
My password is password.

7/10 from me. I found the dated quaintness a plus. Both men and women are heavily made up so they look like painted dolls. A bit patchy as you say but a nice film all the same.