I found the episode pretty good overall and really surprisingly so considering the somewhat lofty expectations and unease (due to not knowing what to expect from handling topics such as body positivity and how hurtful words stay with you) I felt prior. This was a well handled story, starting off with an instigating incident at a water park (that sees Bart & Lisa become quite ill due to a trip with Homer to a closed-off attraction from the old park) before it splits into an entertaining main plot with an interesting conflict between Lisa and Marge (stemming from how the latter called the former "chunky" in an innocent way) & an amusing little subplot about Bart hanging out with local bullies Jimbo, Dolph, Kearney & Nelson in their secret gym. I wouldn't say that this was one of the top best episodes of the HD era, but it is one of the better efforts of the seasons.
I thought the opening with the Simpsons going to the Quiet Rivers' water park (formerly 'Riot Rivers', which Homer remembered it as from his youth) was a surprisingly good one. Some nice gags (such as Homer's memory of it being identical to the criticism video Lisa shows him bar the music, some sign jokes & Milhouse being some swim diaper lover due to fond memories created a chuckle, though it was kinda creepy), but felt they dragged out Homer's initial angry disappointment about the park remade as this super safe place a bit much for my taste. Homer taking Bart & Lisa for one (last) ride at an old dangerous run-down super slide called Devil's Deluge' was fun (nice with the three having fun & solid animation work). So Bart & Lisa get really sick due to the tainted water (cue poop joke about the park evacuated in a panic before the kids have an incident).
Then Bart & Lisa are required to take steroid medication and it that causes them to swell up (Lisa surprisingly less than Bart, who definitely looked fat). I liked the cutaway joke about Bart's praying mantis prank on Skinner (pretty funny) & Lisa being secretly hurt by Marge innocently calling her "chunky" before school was a great bit (with the visual of the word invading her mind like a huge slab of cement) and it gave a nivce scene of her hearing the word everywhere at school (which added to the realism as she cannot stop thinking of it) while Bart revealing to the bullies he has taken steroids and being invited to work out at a secret gym in the school basement. I must say that I was really positively surprised they didn't have anything with neither Bart nor Lisa bullied due to their rotund appearances which was a very nice decision by the writer.
The conflict between Lisa and Marge was the episode's strong point for sure. I really enjoyed how it was building with Lisa feeling all the more depressed about her unfortunate post-medication appearance (I also saw this as a bit of a comment on how some strong medications have negative effects on patients' physical appearance and mental well-being) while Marge sees something is wrong and tries to be a good parent and cheer her up, until Lisa gets fed up and loses it as Marge has her trying out new clothes and keeps mentioning her appearance. There were both some nice humor, like the bystander reactions and Marge's word "flattering" making the "chunky" way worse (hilarious), but the voiceacting was great as well with them increasingly getting angrier and Lisa's tantrum was one of Yeardley's more powerful (and amusing) moments as of late.
Marge enlisting Homer's help to talk with Lisa gave great scene with Homer really trying to be a great father to Lisa (and it was pretty funny, with Homer's thought process being a bit of a highlight) so good scene. Then we have Patty & Selma enlisted to help Lisa feel good about herself (which was a nice move by Homer) as they are used to being called ugly, fat, unattractive, etc. and that led to a fun spoof take on 'Aquarius' from the musical 'Hair' with Patty & Selma singing "The Age of Who Gives A Crap?' (maybe it wasn't necessary, but I found the visuals and lyrics amusing, plus it fit in with the body positivity theme & what characters are better to tackle that than Marge's sisters?). Lisa and Marge reconciling was a nice scene, but then Marge inadvertedly lets two wrong words slip (I actuallyfelt bad for Marge, who just cannot help herself).
Then there's the part with Marge taking Lisa to a hypnotherapist (after a run-in with Luann Van Houten and Milhouse, which was a little amusing but weird with the bath joke) and the scene itself was well done (and I suppose nice detail of the therapist being a breast cancer survivor) & allowed for some introspectiveness with the two going into each other's mind and see the damage, not only for Lisa's but in Marge's mind (with her own mother Jaqueline having called her "plain"). Nice final reconciliation with the two words bothering them shrinking down to a small size and the two sitting down (both apparently still in the mind of Lisa), realizing how much some words can hurt and probably will remain there in some form for the forseeable future (which was a nice and realistic moment, which gave a good message and a nice end note for the story.
And then there was Bart's plot with him hanging out with the bullies in their gym and it was nothing special at all , even though it was nice to see them on a common and friendly ground (even though Bart essentially lied to them, as his steroids were just a part of the medication he had to take to get rid of the infections). It had some nice little interactions and jokes, plus I liked the end with Bart disliking how they suddenly bring in their girlfriends (which to him ruins everything) so he just walks out on them and is back monologuing on the schoolyard in an funny little poetic last moments. I think that this plot technically could have been left out, but I liked it as it did add some levity to counter the dramatic main story & Bart's portrayal was fairly good (plus it is nice to see the bullies not being bullies once in a while). Nice one, even if it felt a little disposable.
All in all, a good episode with some really interesting stuff. Strong main story with the conflict between mother & daughter being great (not only being really dramatic but also a bit funny & also realistic) and I liked the body positivty theme & how some words can be really hurtful (even those that are unintentional) and stick with you for a long time if not forever to some extent (so definitely a relatable, some of which there haven't been that many as of late. 'Bart's In Jail!' certainly comes to mind as one of these, though this one is a much older issue still going strong). Subplot was pretty fun and entertaining despite not completely necessary and a bit throwaway (and I'm a little disappointed Bart didn't actually get swole like the plot description promised. I wanted cursed swole Bart, dammit! Lol) but anyhow still a nice enough little side story.
I'll give it a 4/5. Not one of the best and with some issues (such as why doesn't Homer have any medication-related issues as he got sick too, the weirdo Milhouse jokes were a little much, the body positive messaging could have been improved upon as they felt a little muddled & the subplot was just OK), but it was still fine (not only the themes, drama and jokes, but characterizations and pacing). Nice first effort by writer Juliet Kaufman, great direction by Tim Bailey and nice job by Matt Selman. Standout episode of the season so far. I can understand why this episode failed to some, but I enjoyed it and would like to see more like it (episodes tackle real-life problems rather head-on with interesting drama, nice humor and some realism, like the abeformentioned 'Bart's In Jail!').