Very much in line with your opinion, to me its a 10/10 game most of the time with some mild hiccups that take it down a notch for a couple of moments.
I very much enjoyed the expanded story and much like how you put it, I was very impressed about how they fleshed out the characters turned out to be. Much like in FFXV, you feel for them. The fact that the game its story/character driven makes the linearity of the world design make sense and fit well. Not sure if its the direction I would've picked if given a choice, but it works well here since its done by design and its well written. Maybe the ending is the more divisive point of the game, but I personally like it quite a lot, its very meta and very telling of their intent to deviate from the original story in further installments. I hope that is the case, I like it when remakes are also a reimaginings, because certain elements dont translate well after 23 years. Dialogue being one of them, it threw me off a bit in the begining of the game how Barret is presented. Very much in line with how the original character was portrayed, but im not sure if that was the right call for this interpretation of the game.
As for the more technical aspects, well the game is gorgeous in spite of a few instances of frame drop, but the gameplay- specifically the battle system- to me is the best in the franchise, and I do mean that. I mentioned this since the demo came out, I loved how the mix the active battle system of modern RPGs with the classic ATB system of old, I hope this is a model they reincorporate for future FF games. I absolutely loved it and find it very dynamic.
Other than that and as weird as it may sound I wouldve liked more "filler" content. I feel this had very few sidequest, few missions, maybe an optional post-game dungeon/area with though enemies, I dont know, the usual side-content RPGs usually get nowadays. The game doesnt really need it (most games dont), but I would've liked it as a plus. It doesnt really do much getting the Bahamut summon when theres so little left to do.