"Owari no Seraph" has a good combination of serious and funny moments that makes for an enjoyable read. The moments don't conflict with each other, and the story feels like it flows well so far. There is a nice balance of mystery throughout that keeps you thinking, and overall the story gives off an old school FMA-like vibe.

Personally, I think the main character is a bit too much of a shounen manga protagonist and it doesn't feel like his character matches the vibes the series gives off. Even though this is flagged as shounen series, it feels like it is something that would appeal more to older readers.

Either way, I still enjoyed reading. And, I do hope that you will give "Owari no Seraph" a read too.