I just finished it and yeah, if there's one single aspect of the game I'm disappointed with, it's the story, and the fact that LITERALLY NOTHING FROM THAT AWESOME ANNOUNCEMENT TRAILER IS IN THE GAME. If ever a case were to be made with false advertising for video games, this is it.
It's tragic really. Watching the trailer again, you can tell a sweeping epic of a story with a huge cast of characters and in-depth villains was planned, but tons of money and man hours spent on developing all that, and animating those breath-takingly gorgeous FMVs was thrown away, because not one shred of it is in FFXV.
It's a fun game. The gameplay is wonderful, the world is beautiful, and there's lots to do. Your main cast of four heroes are extremely likable, believable, and you come to truly care for them, but it feels like that all came at the cost of what would have otherwise been an epic memorable story akin to what most Final Fantasy games are known for.
The one exception to all this is the span of time from when you get on the boat to Altissia until you get to Tenebrae. That was the only span in the game, for me at least, that I felt like I was playing a game that belonged under the Final Fantasy banner. Had the whole game been full of moments like those, you'd have an instant classic to rival the best games of the genre.
Again, I can't stress enough that I thoroughly enjoyed the game, and still am enjoying it (there are tons of quests I've yet to complete and I'm having a blast going through them, especially now that I have the flying car to speed things along). I'm just very let down by a plot that showed so much promise pre-release that seemingly got thrown away and none of us will ever get to experience now.