This is one episode that really reminds me of how I came to love Pokemon when I first started watching it at the end of the '90s.
If one was to simply look at the synopsis for this episode, they'd probably find the plot to be dull and uninteresting. However, thankfully the synopsis doesn't tell the full story lol. I thought Gringy City was a very unique place for Ash and co to visit on the back of the likes of Saffron, Celadon and the desert surroundings where Ash caught and released Primeape. Additionally, it was cool how the Magnemite and Grimer families were both introduced in this episode in the grimy Power Plant environment.
Although the Magnemite's infatuation towards Pikachu didn't interest me much, I liked to see a different character to the Nurse Joy and some of the interactions between the characters, e.g. Ash calling Magnemite a streaker, much to Misty and Brock's embarrassment.
However, the surprise capture of Muk made this episode for me. It was right out of left field when you expected this episode to be left as a filler meant only to showcase a couple of new Pokemon. There was no impetus beforehand for Ash to catch Muk, and to top it off it was mostly down to the work of Magnemite/ton that the Grimer and Muk were repelled. So the first time I saw the episode, it was a complete shock when Ash pulled out a Pokeball to catch it. The background music makes the scene all the more epic too. Pity that they don't do spur-of-the-moment captures like this any longer.