Accidental Aesop: Since the reason why Taiga falls in love with Ryuuji is because he was able to fill an empty part of her heart left by her parents and Minori, and for a good majority of the series, Ryuuji and Taiga come off asPlatonic Life-Partners, it can be interpreted that platonic or even familial love can never be as strong as romantic love. In other words, it implies that Ryuuji would've never been able to "fix" Taiga, had their relationship stayed purely platonic. Granted, this may be a byproduct of the series being a romance story, but either way, it has rather Unfortunate Implications.
Adaptation Displacement: The anime series has done this, as happens a lot with anime based on light novels outside of Japan.
Big-Lipped Alligator Moment: Haruta's Christmas dream about his classmates getting naughty. Out of nowhere? Check. Bizarre? Check. Never brought up again? Absolutely.
The ramen chef demonstrating the "Secret Art of Endless Transmigration".
Broken Base: The second half of the series, which goes into Darker and Edgier territory, focusing more on relationship drama than humor, polarizes a lot of fans. The ending does not help. Ryuuji confesses to Minori, but she rejects him because she thinks he like Taiga. He then starts to realize he likes Taiga and confesses to her. Half of the fans think this is an awesome ending, but the other half brings up that beforehand, Taiga and Ryuuji looked more like siblings and he - for about three-quarters of the show - liked Minori and had much more chemistry with her.
Cliché Storm: Although it does play with a lot of the typical slice-of-life anime and romantic comedy tropes, it doesn't make the work worse. If anything, it's proof that Tropes Are Not Bad.
The dub of the second SOS short has Ami annoyed with her director and cameraman over pudding, saying they both have "pudding for brains". This dub was released in 2014, the same year the Twelfth Doctor was introduced, the same doctor who calls people "pudding brains".
In episode 8, viewers are meant to root for Taiga in her swimming competition against Ami, but her plan to win is to pull off her opponent's swimsuit. Although given that Ryuji calls her on playing dirty and she ultimately doesn't win the competition, this is debatable.
Some had this reaction to Kitamura in episodes 15 and 16, where he essentially abandoned his responsibilities, wouldn't say a word to his friends about what he was going through, and confessed to his feelings to Sumire on public stage. Many felt far more sympathetic to Sumire's side as a result. Taiga's reaction got a similar response, since she physically attacked Sumire over Sumire not liking her friend while screaming and throwing a massive tantrum, so it's not uncommon that even fans of Taiga are willing to concede that she deserved the two week suspension she was given for starting that fight.
Some had this reaction to Kitamura's outburst over Sumire. Considering that there was little to no foreshadowing for it, that Kitamura essentially abandoned his responsibilities, wouldn't say a word to his friends about it, and confessed to her on public stage, some felt far more understanding to Sumire's perspective.
Taiga's Love Epiphany and subsequent breakdown at the end of Episode 19 can come off as this, since it's very sudden and rather poorly worded, making it sound like she can never be with Ryuuji again in any circumstance if he gets together with Minori.