Even if the premise (nearly blind little old man acting as if he had good vision) is difficult to accept by an adult, Mr. Magoo is a character that has similarities with many kids' grandparents or elderly neighbors that refuse to accept their obvious age-related limitations, making him situation-comedy funny, and more because of the charm given to him by a great voice artist, Jim Backus (the Mexican voiceover was great too.)
Some of the visuals may need explaining for today's kids of how the things in the 1960s and before worked, like for example very old wall telephones or UHF band television channels. The minimalistic but stylish visual design was good and very modern for its time, maybe too dated for today's taste, although not a problem.
Again, the most difficult obstacle for this show is today's adult mind. The very simplified animation and many of the stories with coincidental plot points, always about nearsightedness denial, make it difficult for grownups to remember how much they laughed at simple, repeated gags during early childhood years.
My bet is that kids can still enjoy this show if not having a zillion other options at the same time and if given the chance by skeptical adults.
