Being able to order characters around and switch between them on the fly improves the game by a huge margin I must admit (on top of teleporting around with the ocarina); the biggest problem I had with the Wii U version was how you're the only one on the battlefield worth a damn which made for some tedious segments of just running like hell between outposts and missions and also killed any feeling of being in the midst of a large battle because you're the only one doing anything against the enemy. The added layer of strategy and character switching really ups the pace and makes the game so much more engaging now, I love it!
The graphics took quite a knock though, and you can see they took some lazy shortcuts by downsizing some images so much they look blurry and just left it at that, and the 3D effect also serves no purpose other than slowing the game down, not worth it just to have your hud stick out a bit more. And of course the poor performance on old 3DS systems.
Overall its pretty damn great though, definitely worth checking out if you're a fan of warriors games and haven't tried it yet, and most importantly have a new 3DS haha.