These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Happy Days
Crowning Moment of Funny: Fonzie's been using "Sit on It!" for years, to great reaction. When Marion of all people uses it on him, the reaction from the crowd and Fonzie himself was priceless.
Crowning Moment of Heartwarming: Joanie and Chachi announce their engagement. Howard, the father of the bride, walks up menacingly to Chachi- "Chachi, I'm going to say something, and I'm only going to say it once: I like you. Welcome to the family." and holds out his hand. Also, when they tie the knot in the Grand Finale, when Howard thanks the audience for being with his family through all these years, and says "to Happy Days."
Chachi was alwaysThe Chachi. He was popular with the girls, but retroactively, amongst older fans? Please.
Seasonal Rot: It started out as a very cool, low-key show, then became the ideal version of a standard sitcom with a Studio Audience. It'd started getting worse (the Trope-Named Shark-Jump) even before Richie left, but only got worse after that. Fonzie got a temporary full-time girlfriend for one season, and things got increasingly worse with gimmicks and nonsense until a thankfully fantastic final episode.