The endless eight arc is unforgivable. There's already a lot of issues with this series that stem from the unfortunate lack of anything ever mattering, but this awful arc takes that to a level that would almost be hilarious if it wasn't so sad. While I can appreciate the fact that the art and directing was slightly different in all eight of the episodes, it isn't nearly enough to fix the greater issues that stem from it.
In truth, it's insulting to the viewers to produce the same story for eight consecutive weeks. If the direction they were trying to go was so incredibly important to the story that they couldn't step away from repeating the same events in at least a few episodes, then the director should have limited it to a total of three. 1) The club goes through the events of the endless summer vacation, 2) The club figures out what is happening, 3) Kon saves the day. This would have had nearly the same impact, without taking an already mediocre high school romcom and making it totally unbearable.
With that short rant out of the way, I'll delve into a few other issues I had with the series as a whole. Most stories tend to either be character or plot driven (occasionally there is something truly magnificent that is both but it's rare, and certainly not the case here). The Melancholy of Haruhi Suzumiya tends to forgo plot and instead tries to drive a fun story with it's "strong" characters. The issue with this isn't the direction, but instead the execution. It's problematic for a character-driven story to have terrible characters, and unfortunately, 4/5 of the mainstays in the series are genuinely bad.
Kon is the only character in the series that is at all enjoyable and even he struggles to maintain a grasp on the viewer's interest after the endless eight arc. Haruhi is better written than the other three main characters but despite that, she's not at all likable. She's both a Mary Stu and a generic Tsundere. Her relationship with Kon is occasionally cute, but I found myself desperately wishing that he wouldn't fall for her because he didn't deserve a life that would be filled with misery, and frankly, that's the only thing Suzumiya was going to offer him. The other three main characters are incredibly 1-d, it's really unfortunate that this is the case because all three of them have the potential to be much better characters than they actually are.
The thing that continues to stick out in my mind as I type this, is the wasted potential of the series. There was so much to work with and instead of actually adding flesh to the skeleton they built, they decided to go the sitcom route, and that only works if you're willing to write truly great characters.
I walked into The Melancholy of Haruhi Suzumiya expecting something lighthearted, funny, and potentially one of the all-time greats. What I got was a 26 episode high school romcom with bad characters and an episode that repeats itself 8 times.
3/10 do not recommend unless you've seen thousands of other series and literally have nothing else to see.