Other than Breath Of The Wild, which I'm assuming you already know you should have played, this is one of the very best, and longest, games on the Nintendo Switch.
Three Houses is filled to the brim with tactical combat and deeply strategic party management. It's got a winding, engaging story, and features elements from other genres, such as simulation and education.
It isn't a stretch to say you'll be putting in 60 hours on the low end. For those who have to explore every nook and cranny and find every secret, 100 hours isn't inconceivable.