Perhaps I'm a bit biased here, but this film was my first exposure to Abbott and Costello, and I've loved them every since. My parents bought the VHS tape of this when I was very young and I was instantly mesmerised -- those guys were the funniest team of comedians I'd ever seen. They still are, really.
In retrospect, this may not be one of their greatest films (it's not on par with Abbott and Costello Meet Frankenstein, for instance), but it's a fun retelling of the classic Jack and the Beanstalk story, casting Lou as Jack and Bud as the crooked butcher who swaps him magic beans for a cow. Transplanting the boys into the fanciful setting works, and although some of the stuntwork and sets seemed pretty threadbare at times the story and the comedy still click well. This is also one of the few films the boys ever made that could be classified as a musical.
For completists who love Abbott and Costello and are still impatiently waiting for the rest of their films to come out on DVD, this is a must-have. Also recommended for folks with kids -- it's a wonderful movie for the young.