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.
Crowning Moment of Awesome: The group winning number one on Show Champion with "Mamma Mia", especially after all the crap they've been through in the last little while. It's heartwarming as well when you see Hara and Gyuri making open efforts to be friendly with Youngji.
Ear Worm: Most of their songs after Sunghee left the group and Hara and Jiyoung joined. Special mention goes to Mister, Wanna, Step and Lupin. Also "Mamma Mia", their first song after Jiyoung and Nicole left.
Wanna is such an Ear Worm that Pump It Up Fiesta, which includes the song (among other K-pop songs), has a course that consists of the song five times in a row.
Ensemble Darkhorse: Youngji. At first she was deemed an unwelcome interloper, but now netizens are saying she's "saving" the group.
Face of the Band: Hara, who is officially the face of the group and is the most well-known.
Never Live It Down: Seungyeon stole Nicole's solo time to show off, ruining the group's choreography and causing Gyuri to give her an epic Death Glare. Fans have not forgiven her for the questionable behavior. While I-fans are more generally forgiving than K-fans, they don't make an exception for her. This is always brought up whenever there's an article about her and it's getting worse now that she keeps landing lead roles in tv dramas, but her acting skills are nonexistent.
Averted with Goo Hara who is in fact one of the most if not the popular member of the group, despite taking Sunghee's place. Her immense popularity still remains despite it faltering now and then, for example after her scandal which made her the target of netizens' undisguised loathing for a while.
The new member YoungJi was set to be this with a rather cynical welcome, however she has so far averted it and become very well-liked amongst both the public and fandom.
Tastes Like Diabetes: Honey, as the name would imply. It's more the concept than the actual song though.
Of course this is about the most subjective trope the tech demo evokes. Some people praise it for finally overcoming said valley, since Kara very closely resembles her voice actor and a real human in general (you can see the muscles move under her skin and her nostrils flare as she speaks). Other find that she still isn't human enough.