In many ways, Ub Iwerks was a cartoon genius. He was much of the driving force behind creating Mickey Mouse and his contributions to the field are immense. However, when Ub went to work on his own, his results were less than stellar. From 1930 through 1936, he made several dozen mostly forgettable cartoons--cartoons that never seriously rivaled the quality and style of Disney or even the Fleischer Brothers. If you've seen many of them, you'll understand why the cartoons failed....as the years passed, Iwerks de-emphasized humor and put a strong emphasis on singing and cutesy characters...uggh!
In the case of "The Queen of Hearts" you have a lot of singing and nonsense that is frankly not much fun to watch. I definitely found my attention wandering mostly because the edge and humor were missing. The Jack of Hearts is a jerk and steals the tarts that the Queen made for the King....does that sound like 8 minutes worth of cartoon to you?! Despite some nice animation, I say skip it.