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

Was the ending of the Attack on Titan manga really that bad? The

Meh endings are a very common problem with the genre, not

Shingeki no Kyojin - 04 - Lost in Anime

Shingeki no Kyojin (Attack on Titan) - generic discussion thread

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Shingeki no Kyojin - 04 - Lost in Anime

80 Anime Like Attack on Titan

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Spring Anime Catalogue 2015 – METANORN