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.
Americans Hate Tingle: Good luck finding fans of this anime in the west. You have to tilt your head and squint a bit, but they're there.
Art-Style Dissonance: Some found seeing Lilo's daughter and Yuna on the same screen together to be a problem. They're near the same age yet the latter is much taller than the former.
Audience-Alienating Premise: A Stitch anime isn't a hard sell in of itself for Western fans. However, leaving out Lilo with no explanation as to why she, Stitch's ohana, would ever get separated from her in the first place until the third season is enough for them to not want any part of it. The dub arguably makes it worse by explaining it away in the first episode as Lilo getting bored with Stitch after getting a new boyfriend. Mind you, it was Jumba saying it, so that doesn't mean it was correct...not to mention the dub of the episode where Lilo comes back gives the same explanation as the original version did.
Ho Yay: The Ho Yay between Jumba and Pleakly is possibly even more ridiculous than it was in the original—when they're "reunited" in the first episode, they reunite with a tearful embrace and much sobbing from both parties about how much they missed one another.
In one episode, while Jumba and Pleakly are helping the postman deliver a letter to Yuna:
Postman: "So, how long have you two been married?"
The English dub goes out of its way to exacerbate it.
Seasonal Rot: Even amongst people who liked the series, the third season gets a lot more heat due to switching the setting from Izayoi Island to the urban setting of Okinawa New Town and switching from the focus on yokai and urban legends to Slice of Life.
So Okay, It's Average: Some view it as mediocre, mainly in comparison to the original movie as the anime was more of a Gag Series. There were also complaints about how Stitch's cuteness isn't so subtle anymore, although that's par for the course in nearly every Stitch related endeavor in Japan.
Tear Jerker: Just try and watch the third season episode where Lilo comes back without feeling sad or having a lump in your throat, just try.
They Wasted a Perfectly Good Plot: Some were expecting an anime based on Lilo and Stitch to be more action packed and full of adventure. Some were expecting something closer to the actual movie in tone. What they got was a Gag Series.
The anime itself had a pretty interesting setting, being in the Okinawan islands of the Ryukyus (in the first two seasons). We could've learned something in here along the way like how the series, at times, highlighted their own culture (dances, beliefs, language, etc.), then sneak in some genius bonuses along the way. It might have made the show feel too similar to the former but it'd have still worked as an interesting counterpart. Well, there was the yokai and karate, but it should've done more.