There are very mild spoilers about the anime's storyline. Synduality: Noir started wonderfully well and would get a 10 out of 10 from me. In time it had one or two not too great episodes, and then its first season ended with a great three episode run worthy of 10/10 again. Actually, Synduality: Noir has many great points. It has a great main character in Kanata who is a wonderful shonen anime hero, maybe one of the best, and you just watch the series for him. Moreover, the world-building is good (to be honest, far better made than many Star Wars animated series), there are mysterious supportingcharacters, a fun and unpredictable mentor, and a good collection of great side-characters. Also, it has great mecha battles.
However, the anime has four main storylines and the fourth makes things less good. The first storyline is about the fight of humanity against Enders, some sort of life form that tries to eradicate all humans. The second is the battlefield development of the main character Kanata. The third storyline is the mystery surrounding the Magus (robot) Noir and the legendary city of Histoire. However, the fourth is just your boring old harem storyline, and that makes things bad for such a well-designed anime series. As it also wants/needs to serve as a harem anime, then we have the must-have for harem but unnecessary for any other purpose swimming pool adventure episode; and, after that, we go back to more serious adventures. I wish they could just give up on having a harem side to the series as it would be so far better. At the moment I give it a 9 out of 10 because even though it has a harem element, it is still a great story and it is very well designed and very well executed.