Well, I mean, a person could make the same argument of "It's not meant for adults" about every single thing related to Disney if that's their excuse for something being subpar or outright bad, not just this particular TV show. Which is why that argument is nonsense--Disney products have always been for the entire family and consumer base even if children are the primary audience. Sort of ironic to see that kind of insult and/or dismissive aside used on a Disney fan board where everyone are adult fans of Disney products of all places, you'd only be insulting yourself really..
Rapunzel's Tangled Adventure is aimed for an even younger audience than this show, I'd say, and it's better than this one (even if TLM film runs circles around the
Tangled film), I feel that's objectively undeniable. The
Aladdin series was the best back when of the film-based series, but
The New Adventures of Winnie the Pooh was pretty good as well. The best episode for me was the one where Ariel gets stuck in the whirlpool because she can't get the gold bracelet off and she's afraid to go home; the animation in that was is incredible and there's quite a bit of horror there, an element that I like because it's also present in the original film (mostly with Ursula and the polyps, but even the scene where Triton destroys her grotto and the shark scene). There's also a bit of horror in "The Evil Manta"--strictly referring to the beginning with the creepy voice asking to be released--as well as ones like the episode with the Red Tide, the one where Ursula nearly takes over with that weird magic box, Ariel being cursed to cause calamity when she laughs, etc. I also like "Calliope Dreams," "Red," "Stormy," "Trident True." "Marriage of Inconvenience" is an interesting episode because it introduced some other kingdoms, even if overall it's not very good. Same with "Ariel's Things" and Ursula using Atlantica's hatred of humans to help herself, it's an interesting idea not executed very well. There are a few episodes that are merely light-hearted fluff that are still quality as well (like "Whale of a Tale").
That said, I always loved the episode with Ursula and the bad luck creature even if I know it's not that great. I mean, the plot is a little stupid. Not the part with the merfolk hating an innocent creature because of old wives tales and myths, that's the best part, but the idea of Ursula being enraged by the creature is a little silly. I do like that she stopped by Atlantica and showed her lack of fear of Triton in that scene though, and that they give us a glimpse of a "thin" Ursula.

And I always liked Urchin and Gabriella as well, even if some of the episodes they're in are on the weak side. I guess really, as I'm looking over the episode list, most of the worst ones are in the last season. It's not just the animation quality, but the stories that aren't great other than "Heroes" and "Ariel's Treasures." Maybe I'd have had a fonder impression of the show if the show had only had the first two seasons, I guess?
@
D82: I never watched much of
The Emperor's New School. It's another one like BH6 where the animation is so bad... I kind of wanted to since I think Yzma
was featured on the show, right? (Not sure if voiced by Eartha Kitt, but still.) The only TV series I regret now not watching was the
Lilo & Stitch one. I was very cold on L&S (the film) other than Nani and the Grand Councilwoman characters (and the animation is great, too) for the longest time, and the show came out around that period in high school when people sort of make you feel ashamed of liking anything Disney--I'm sure we've all been there--or, if you're a guy, of liking anything that's even vaguely "girly" because of... IDK, the colors used being pink / purple or most of the characters being female or romance being involved, there's singing, whatever, it's all garbage. Only recently did my opinion shift on the L&S film a few years back, so I kind of wish I could see the TV series now. I watched the sequels back when my opinion first shifted and I thought they were okay.