Loving the game so far. I'd recommend to download the Japanese voices for those who don't mind about them, because I think they feel much better that the English VA. Still, about the game, I don't see a decline in quality with the previous entries, I'd say the opposite actually. I love the characters so far. I prefer the balance of a more light-hearted tone with more epic, dramatic moments. I'm really digging the combat system, even though at the beginning I felt it was a bit slow, it's also more strategical. It's more forgiving than XCX because it introduces new gameplay mechanics slowly. Some people might be put off because of the rythm, but I get that there's too much to digest, so I don't feel it's a bad decision. XCX was critized for the opposite, so they actually heard the feedback and the game is more accesible from the start. Side quests so far are a middle point between XCX and the first one. It was my favourite part of XCX, it was the worst part of the first one imho, and it this game they just feel right and fair. Also, some of them are more meaningful. So... I'm pretty happy about these first 15 hours. I obviously have to play way more of it to make a final decision, but.... I would say that it's probably another case of a Monolith Soft game being a bit underrated. Not because the scores are bad, but because I feel that they still make the best JRPGs in the market, and I don't feel like people appreciate the games enough. But, well, different tastes, I suppose.
I'd say that people who loved the first one will find this one great. Not sure of the people who prefered the more open-world ended nature of Xenoblade Chronicles X, but I doubt that they won't find a lot to enjoy about it.