It's really, really great! I'm a first-time player and I picked it up when I bought my Switch and so far I'm loving it to all hell! The game mechanics are copious and very deep, and there is a LOT of content to keep you busy for hundreds of hours. It's really over the top and probably the best tactical RPG I've played. The story is also entertaining, and is basically a parody of a lot of Japanese manga/anime tropes. The game is also self-aware and pretty funny at times.
You can probably read a review to get a grip on the gameplay, but let me tell you something else -- It's practically meant for the Switch. Seriously, this game is fun in 5 minute bursts or 5 hour bursts. You can take your Switch with you and whip it out for a few minutes like a mobile title and then relax at home and enjoy it for hours on end. In addition, it's very light on the battery. I get a solid 5 to 5.5-ish hours on full brightness with airplane mode off. That's impressive! Plus, the UI looks clean and nice on the portable screen. Honestly, this game doesn't feel like it fits on PS4. The UI, the gameplay, everything just works so much better on a portable system.
In all, I highly recommend this title. It's one of the best games on the Switch currently.