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.
The increased Moe elements are seen as either new and refreshing or as desperate and creepy otaku pandering.
The character designs. Some love them, others find them gaudy and trying too hard.
Contested Sequel: due to its episodic, goofy nature (to the point that it feels more like a spoof of the genre), childish writing (with both the Myth Arc and character growth being non-existent), Though subverted as it was alledgedly very financially successful (though mostly only with otaku).
Turns out, the reason for no plot is Shōji Yonemura, the lead writer of Kamen Rider Kabuto (which suffers from the same plot problems), also wrote for this show and wanted it to be "simple".
It really says something when the most popular character is a villain (Wolfrun), and not even the main one. It also says something when its first SH Figuarts figure is the Ensemble Darkhorse otaku character (Yayoi/Cure Peace) and not the leader.
The "Nissan Combination" (Nao and Akane) is also highly widespread and pretty much rivals Nao/Reika in popularity when it comes to pixiv fanart.
In the non-yuri side there's Miyuki and Wolfrun, which acquired quite a bit of fanart at pixiv as soon as the first episode aired.
Foe Yay Shipping: A lot of people on pixiv like pairing up each of the Cures with the villain they fought in episode 23. note Meaning Sunny/Wolfrun, Peace/Akaoni, March/Majorina, and particularly Beauty/Joker. Of course, this means Miyuki is left over—fanartists are split between keeping her single or having her and Sunny compete for Wolfrun.;
Flat Character: A common complaint is that Smile seems to go out of it's way to avoid having the characters grow or change.
"Funny Aneurysm" Moment: Episode 9 is an April Fools' Plot where Yayoi lies to Miyuki about becoming a New Transfer Student somewhere else. This lie soon spreads to her entire classroom since Yayoi unable to say "April Fools!". Eventually they hold a "going away" party, and Yayoi is given the chance to admit this lie. However, she can't bring herself to do so because she imagined that it would go From Bad to Worse where everybody would abandon her for being a liar and that "They'll be really mad... They'll all hate her" and "nobody will talk to her anymore". The very next year, a show called Kotoura-san premiered with a Downer Beginning that pretty much made this nightmare a reality for its titular heroine in a much more dramatic sense. To top off the awkwardness, this doubles as an Actor Allusion—both Yayoi and Haruka Kotoura were played by Hisako Kanemoto.
Idiot Plot: Episode 14. Ever hear of cellphones, girls?
Internet Backdraft: The massive rumors about a Saban Brands show being created called "Gangnam Girls". After they found out that the plot was extremely similar to Smile's, the fandom assumed Saban might have gotten the rights to Smile and got up in arms because 1) they changed the title, when Smile Pretty Cure is already an English title name and 2) giving a Korean name to describe a Japanese anime is a little on the offensive side.
It's been found that Saban couldn't trademark "Gangnam Girls" and they may be changing the title to "Glitter Force". Which is somewhat better.
Launcher of a Thousand Ships: Nao Midorikawa. She is mostly shipped with Reika and Akane, but after Episode 18, Nao/Yayoi fanart began to surface, and after Episode 23, she gets shipped with the Beautiful All Along Majorina. And then there's Episode 25, which ignited more Nao/Akane shippers.
The fandom tends to portray Reika as a Yandere after the shot of her watching the girls from behind a door reached Memetic Mutation levels. Nao/Akane shippers from Pixiv playfully use this trope on her. Minor classmate Hiroko Kanemoto also gets this treatment combined with Stalker with a Crush.
Moe: The fandom thinks of Yayoi as this, if the large amount of fanart she got on Pixiv after the first website update is anything to go by.
The show as a whole emphasizes Moe and Kawaisa elements more than other seasons of the franchise.
Mood Whiplash: In a complete coincidence, in the 13rd episode ending, news flash appear about a bus accident in Japan which costed 7 lives and 38 injured men. All while the screen shows the Precures happily dancing and the aesop of the episode is 'bad luck will go away if you smile'. Errr... yikes?
Moral Event Horizon: While he doesn't actually cross it by virtue of being Brainwashed and Crazy, Straw NihilistJerkass Wolfrun at the very least proves himself to be a Not-So-Harmless Villain in episode 40 when he tries to kill Miyuki as part of a vendetta against Akane and everything she cares about. Smashing the precious charm her friends made for her earlier in the episode was at worst a slightly extreme example of Kick the Dog even for him, but this is the first time a Cure has ever found herself in mortal peril.
Narm Charm: The characters are almost self-aware that they are supposed to be larger-than-life characters in a fairytale, leading to this trope. Especially Miyuki.
The Producer Thinks of Everything: A minor example, in the first ending's Cure Peace variation where she face plants, her face is red afterwards. This is the only time this happens.
The Scrappy: Candy is disliked for her annoying nature, plots being kicked off because she acts like a moron, and generally being useless. It doesn't help that she's also somewhat of a Spotlight-Stealing Squad. Her older and more mature brother, Pop, is not only more liked than her, but fans express disappointment that he's not the main fairy and is a minor character who only shows up every now and then.
Visual Effects of Awesome: Aside from the series animation being pretty good overall, the first ending's CG animation is GORGEOUS, rivaling big-budget movies. The animated movements are also amazingly lifelike.