For many, this will be an unhappy short, as it has "cruel" slapstick and Mickey Mouse and Pluto are often sad. Other people will find it funny because they will like slapstick. Some people will love it because it is beautiful and emotional.
In this Mickey is trying to earn money at Christmastime with some music, with Pluto as (probably) his only companion. Meanwhile, a spoilt and horrible toddler spots Pluto out the window and declares, "I WANT DOGGY!" Later (when poor Mickey's instrument is broken) he sees a poor family with no Christmas merriment and Mickey is determined to do something...
This short is emotional, beautiful, sad, well-animated, well-plotted and exciting in places. Good for any Mickey Mouse fan and good for people who are not too upset by sad and emotional things. If you are particularly a despiser of upsetting slapstick (especially with the lovely Mickey Mouse), this is not the thing for you. Otherwise, you will (almost definitely) enjoy the lovely "Mickey's Good Deed" for this coming Christmas day!