If you've come this far into the series, you might as well continue.
I enjoyed switching between teams and the new characters a lot. The new "area" is great and easy to get addicted to, especially in terms of exploration and rewards. Pros: If you've enjoyed the Cold Steel series, you'll enjoy this one. Make sure you've played the Crossbell arc to fully enjoy the story. LOTs of characters you can use in battle, and the game gives you sufficient opportunities to play with all of them. The minigames and Daydreams are a nice addition too. Cons: The absolute massive number of characters you have to manage (I think 40+). Although the game makes leveling up characters relatively easy, it's still a bit of a PITA. I would've personally preferred to just stick to a smaller roster with characters with higher significance in the plot. tl;dr I got post-game sad after I finished this game. You should definitely play it if you've already played all the other games.