I'm just answering the question of the topic without entering in details, if i will know that FE writers are reading this, i'll obviously try to explain myself better.
I don't even really know if i can explain this to you with my poor english, but i'll try a bit.
So, feel free to make fun of me
One thing, for example, that has became worse than previous chapter (for me), are dialogues.
They seems too (hope this term makes the idea) "plain" compared to Tellius saga, especially Path of Radiance.
And there are a lot of side/personal stories i found interesting, just mentioned, like Taguel race, Chrom's father, Aversa and the story/mitology of Ylisse and Valm or also the explenation of the connection between them and the old continents.
I would have liked, for sure, different new ideas then the usually dark dragon/master behind a dark cult behind an evil king.
And in the end, i found the story go a little bit too fast.
Written in this way seems i dislike the entire plot, but it isn't so, i would only preferred more in depth and some new ideas (like the time travel of the cildren)
However, i know i played these games in another language, and we are famous for terrible unfaithful adaptation of everything (but sometimes also most epic and archaic, like the Saint Seiya one), and all of these are my personal thoughts that anyone can found wrong or silly.