The advantages:

Turn 1 gives you the choice between buffing damage or defense.
Turn 2 allows you to pull off one of three jutsu that initiate a combo.
If the enemy shuts down one of your guys then you still get combos, just smaller ones.
Lots of High/Low float redundancy.

The main disadvantage is how bloody squishy Midnight Blade is... yet he's the tank when you have no way to keep him alive turn 1. No control, silences, or interrupts. One combo and he's toast.