I honestly never know how to handle handheld impressions, but as long as it's not a Xenoblade 2 or YSVIII/IX level of mess, it's all good, I consider it acceptable as long as it runs like, for instance, Xenoblade DE. No way I'm playing this docked or in any other way, jrpgs give their best on portable consoles.
It's sad tho that exclusive stuff is not well optimized, things like Atelier Ryza are perfect and gorgeous on Switch screen
edit since the ost leaked, I'd love to hear a full on version of the level up theme, but I don't want to risk my spoiler free status