Meh endings are a very common problem with the genre, not exclusive to AoT. It's very hard to find a good Shonen ending that managed to please everyone. : r/ShingekiNoKyojin

MangaReview: (AoT) The Mediocre Ending for a Monumental Epic.

80 Anime Like Attack on Titan

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Spoliers ch.139] The Translation Error

80 Anime Like Attack on Titan

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Spring Anime Catalogue 2015 – METANORN

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The ending to attack on titan is one of the most overhated and

romance Chua Tek Ming~*Anime Power*~ !LiVe FoR AnImE, aNiMe FoR

Spring Anime Catalogue 2015 – METANORN