I found this to be...
...very sad. It's about two old men who are suffering from what appears to be dementia. As someone who has taken care of someone with this ailment until they died, it hit a little bit too close to home. I didn't find it funny. I just found it depressing.
This isn't to besmirch Burns and Matthau, I usually enjoy their work going all the way back to their beginnings, but I just can't laugh about dementia patients, and their nephew getting mad at them at every turn.
I don't understand the high rating that it has.