While everything related to Ouran can be reliably entertaining and any excuse for eye candy is always welcome, the Ouran movie's biggest problem was that it lacked a 'movie-worthy' quality.
Effective movies based on a live-action drama series should relate to the series in some way. Ideally, they should be the climactic conclusion of the series as a whole, solving all the unresolved issues that couldn't be solved in the series' conclusion. Alternatively, they should present a significantly more complicated, multi-layered problem - a problem that would justify taking a movie-length amount of time to solve, instead of a typical episode.
Given there was ample content in the Ouran manga that was not explored in the live action, it was a huge pity they chose such a lackluster major 'complication' for the movie.
WARNING: MAJOR SPOILERS (image heavy and long)
What the Ouran live action did well, in the movie and drama, is the styling and casting. Almost all the cast embodied their roles very well (except for Honey-senpai, whose actor seemed to be awkward with Honey-senpair mannerisms and straining to reach a Honey-senpai-worthy pitch in his voice...to be fair, it's not an easy - or potentially possible - task)
I love Yamamoto Yuusuke. Born to be Tamaki. Perfect casting.
The computer animation/special effects were the cheapest and most fake-looking aspect of the live drama, but I do have a ridiculous soft spot for the バカ brick
Haruhi's actress could have been more dramatic in her emotive moments but she had that serene, understated and unflappable Haruhi quality.
I'm going to go right ahead and jump to the biggest weakness of the movie - Michelle Monaru and her general storyline.
I felt her story contributed almost nothing to the overall narrative or any character development. I'm fairly certain Princess Michelle (which was her manga inspiration) was one of the more minor arcs in the overall scheme of things. My pet peeve is when movies introduce completely new characters out of the blue, whose actions and problems have no relation to issues left unexplored in the series.
The entire crux of the Tamaki storyline and most of Haruhi's storyline in Ouran is about family, but, importantly, about parental issues.
Michelle Monaru brought none of that. Her big 'problem' revolved around her older brother - a dynamic which none of the characters, least of all Tamaki or Haruhi, had experience or problems with. They barely touched on her connection to Tamaki's mother and even that was only in physical appearance. Tamaki was obviously not attracted to her and the 'Arranged Marriage to a Rich Girl By the Evil Matriarch' plotline is done to death.
All in all, she didn't add anything that hadn't already been explored.
Personally, I think they should have gone with the Kanoya arc from the manga, if they had to introduce another female character from the manga. Her resemblance to an 'idealised' Haruhi presented one of the only 'real' challenges to Tamaki and Haruhi's relationship and her angst about her father paralleled Tamaki's mother issues, allowing him to see parallels between his situation and her's.
For all the drama, Michelle Monaru's dilemma was ridiculously simple to solve, plot-wise, which is why it felt super underwhelming. It was just not big enough as a plot to frame the entire movie.
I had no idea Nickhun was acting in this. I've never quite understood his appeal, but it was kind of funny to see him randomly in here.
As much as I appreciate it must be hard for the actors to act in English (well, Nickhun is apparently fluent so...er), the conversations were so stilted and slow that it was hard to sit through. Also, perhaps just personally, but their relationship read more like romance than sibling love to me?? It incorporated a lot of romantic drama tropes. I kept expecting they'd kiss at the end.
Michelle Monaru's storyline also detracted from the exploration of side plots, which contained frustrating little hints of manga storylines - the Hikaru/Haruhi/Tamaki triangle, Tamaki's mother, Tamaki's reliance on the notion of 'family', Tamaki's grandmother and Haruhi's future plans...all could have been ample material for a movie, but they had to rope in a clunky, new plotline that didn't complement or enhance any of the other plotlines.
The Hitachiin twins' big fight would have been a much more compelling 'sibling issues' plotline, if they chose to make that a thematic focus.
(these are real twins! I will never get over it)
Kyouya did a lot of unnecessary brooding?? (what was he really doing in the movie?)
Tamaki's father was priceless. The KISS was priceless.
For some reason, they keep villifying Nekozawa-senpai in the live action? They did so in the beginning few episodes of the live action and I want to know why, because he's just so bishounen-like and innocuous in the manga. The entire race was so stupidly hilarious and awkwardly dramatic. I'm not quite sure if it's a good or bad thing.
For the most part, I enjoyed the Tamaki/Haruhi progression and the incorporation of manga elements (the love quiz!) but they had so much to work with and they chose to leave a lot of it hanging.
I can't believe they went to all the trouble of getting her the OOTORO RING and then just leaving that plot! The ootoro ring and kidnapping was a pivotal moment in the relationship and they just...dropped it all ):
They even alluded to the Japanese festival setting where the events of the manga took place ):
Okay fine, they were adorable. BUT I WANTED MOAARRRR
Know that everything was super awkward after that, in true Ouran shoujo-manga subversion style
Bless Ranka and his loving お父さん heart.
Tamaki's fall was definitely a major climax and really triggered Haruhi's memories of her mother's fall, but I was disappointed at how lackluster the aftermath was - it was just like 'HI GUYS, I'M BACK'.
The accidental kiss was so awkward. I was going to screencap it but then I decided not to spoil every moment “ψ(｀∇´)ψ
This is my Ouran manga pedantic monster coming out but Tamaki never explicitly says that the kiss is okay because he's Haruhi's 'father' (I think it was after the kiss that his whole dilemma starts). I loved the subversion moment in the manga where they're both like 'ah okay, no big deal' and the fact only hits them afterwards.
Some nice moments of cinematography...
Overall...the movie was entertaining, well-styled and full of typical Ouran wackiness. Nothing was too weird or out-of-character to pull me out of my enjoyment of watching the movie.
However, as a Ouran manga fan, I can't help but feel like it was a huge missed opportunity, plot-wise. I'd really hope for a second movie to come out but I don't think that's happening so I guess my dream of seeing the second half of the manga be represented in some form won't be fulfilled ):