In CLANNAD, a nice way to rate an episode or route is to see how much Sunohara appears, and this episode had a ton of Sunohara. The more Sunohara we have, the better. I’ll rate this side story 4/5 Sunoharas.
But seriously, Sunohara was just hilarious in this episode, which surprisingly, as @EisenKoubu said, continued The reunion of the Furukawa bakers while changing the writer. This struck me. Is this episode some fanfiction KEY wanted to include but Maeda refused to write? Sincerely, this is a question I’d like to ask them directly if they appear in another convention.
This aside, while it surely was a fan service episode, I thought that it was outstanding in spite of its fanservice episode status. It was hilarious without having to explicitly exploit the fact that they were all naked, and it also delivered a heartwarming ending without it being too cheesy. Brilliant execution I must say. The reason I’m not rating this a 5 is because even though I found it splendid, I thought it lacked that something inexplicable that you can find in Akio’s side story, or Koumura’s one.
Overall, a very good side story. You shouldn’t be misled by its title. This is a quality-comedy episode, at least in my opinion (not that it’s high quality comedy, but rather that it’s very well executed).