I've been playing Golden Country for a few hours so far, and so far I really enjoy it. It feels different enough from the base game to stand on its own, and adds some cool new features, including one that seems right out of Xenoblade 1. Appearance-wise it looks nice, and the soundtrack is great as usual.
Can't say much of the story yet, but I just got the 3rd driver which seems to be most (maybe all) of the main cast. It's interesting seeing Mythra, Brighid, and even Aegeon interact with their new drivers, and I like the more mature relationship Jin and Lora seem to have. I already cried a few hours in, so it gets going pretty fast!
Probably my favorite part so far is being able to directly control Blades now, both in combat and during exploration. My series of "Mythra standing in front of landscapes" screenshots will only get better!
My impressions might change as I get further in, but so far it seems like a very solid expansion.
NNID: Zephyr25 / PSN: Zephyr--25 / Switch: SW-4450-3680-7334