Awesome Art: The vibrant, lushly-painted backgrounds are gorgeous, while the character designs pay homage to the work of Beano artist Leo Baxendale as well as classic Nickelodeon characters.
Base-Breaking Character: The title character himself. Several viewers view him as having an unappealing design, bland nasally voice, poorly-adapted personality, and in some episodes he acts like a total whiny jerk who gets away with everything. Some also think that he hogs too much focus away from Zeke, Marsha, and most of the side characters, to the point where the supporting characters are disappointingly underused. However, other fans find his extremely goofy personality and childlike energy to be Adorkable and truly funny, while others came to like his character more after the Season 1 finale.
The biggest one would have to be the green swamp girl Judy, due to having an adorable and appealing design. She only ever appeared as a one-off character in the series in the appropriately named episode "Hey Judy". (She also made 3 smaller appearances in the series.) Judy's voice actor, Sarah Nicole Robles, would later go on to voice Luz in The Owl House.
Grossout Show: Grossout jokes are an ongoing theme throughout the series (for instance, Billy's experiments frequently involve the earwax, sweat, snot, etc of the subterranean creatures) but whether it's a defining trait of the show is a matter of the viewer's opinion.
Narm: The infamous Tear Jerker line can sound a bit immature with the way it's worded, somewhat killing the mood.
It's Short, So It Sucks!: The series aired only thirteen 22 minute episodes and lasted less than two weeksnote June 3, 2017 to June 15, 2017.
Ron the Death Eater: The title character himself falls into this. While he is a Ditzy Genius and The Klutz, many people are making him out to look like a complete sociopath who likes to ruin things for fun and abuses his friends for his own amusement. (Which he never does in the actual show.) He's just a good natured kid with bouts of selfishness and naivety.
Screwed by the Network: The show was released on a very rushed schedule over the space of just 12 days, with very little advertising or promotion.
So Okay, It's Average: The show itself, largely because many viewers consider the title character less interesting than Zeke, Marsha, and the supporting cast. However, in recent years, people have started to look past the show's flaws and come to appreciate its humor, art design, and generally lighthearted, unpretentious tone.
They Wasted a Perfectly Good Character: Judy is a fan favorite for a number of viewers, but she only had a significant role in one episode ("Hey Judy"). It's understandable given that the series was finding its footing, and other characters had more active roles and quirks that were easier to write for; however, many viewers would have liked to see more of Judy's cute and kind character. Aaron Springer declared that she would've gotten far more screentime had the show actually received its' 20-episode order.
