For the sake of avoiding spoiling the game I'm going to wrap the rest of this post in code tags.
To me, the Jugdral games were the best story wise (where one game has you on the losing team for the majority of the game plus the capture mechanic made for more unique situations than other game in the series; Radiant Dawn also tries to have this but bails too quickly on them to focus on the peeps from the last game), although the Emblem Saga games were probably even better provided they ever get finished (which will probably never happen considering the clusterfuck the Emblem Saga games were).
I was hoping that my initial impressions with the plot were more due to the finer points getting lost in translation rather than the actual strength of the plot but I was wrong. The game did have some points I wasn't able to pick up on like Plegia's aggression stemming from Chrom's father's shenanigans, but like many other things with the plot, the game only told and did not show. And yes, the game has a decidedly more 'anime' (for lack of a better term) plot than with other games (well, closer to 6 and 8's plot compared to the others) but the game's power of friendship theme was just as disappointing as I feared. I think though the two biggest problems with this game's plot stems from a) the lack of a decent support cast (discounting the major antagonists i.e. Gangrel, Walhart, Validar, Aversa as well as peeps like Emelina, Flavia, and Basilio, who do you have left? A Ferox border guard? A captain of the local Pegasus Knight wing? Walhart's goons? Say'ri and her brother? Tiki? Virion even?), and b) the fact that, while the game has a broad scope (two whole continents instead of one or part of one), it was seriously lacking in the details (only four nations, which is less than even Magvel had in Sacred Stones).
As for the supports, my problem with them stems from the fact that they're mostly there for the lovers/breeding/eugenics purposes with very few options for those who aren't looking to get into somebody else's (fugly) pants. And while some of them are pretty good a number of them are just "Here's my quirk!" "Why that quirk doesn't really sit well with my quirk." "But when I put my quirk together with your quirk, we make for a quirky pair." "That's so quirky I might just make our quirky pairing permanent. Marry me!".
Now granted, there's more to come from the DLC, but just with the base game's plot and characters, there's quite a bit left to be desired. And this is unfortunate since it means that you have to effectively pay double to get the full monty. But at least the core gameplay is solid enough to make the base game feel like a complete game.