A nice bonus chapter, sort of a microcosm of the main game in a way, complete with side quests that range from trivial to a somewhat involved set of fights and somewhat endearing side characters. I liked the sub-plot in Mysidia, and the new powers you get from the DLC are a welcome addition that I can picture making good use of in the other optional content the DLC provides, or a second playthrough on NG+.
When the developers said that the DLC would not change the ending of the game, they meant it. It was not a ruse or a long con, the ending is unchanged.
It's more FFXVI; if you liked or did not like the base game, I don't think this is going to change your mind about it.