One/three advantages:
*.A simple move when in the air that has been shown to be fatal, eg, Kakashi vs Nadare Rouga.
*.Easily worked into other Taijutsu skills thanks to it's simplicity. The Dancing Leaf Shadow would be a good combination for this.
*.Since the enemy will have severely limited movement, escaping is difficult.
One/three disadvantages:
*.Requires the user and target to be in the air, to initiate the attack, and gain enough momentum for the required force.
*.If the enemy can shift their center of gravity, like with the weighted boulder technique or the expansion technique, they can use it to turn the jutsu on the user.
How you would use it in battle:
Using the Dancing Leaf Shadow and other Taijutsu skills to get the target in the air is the best way to use this technique, but it requires the user to have a big opening to exploit. Other than that, using this to paralyze the enemy, then finishing them with something fiery... Sounds awesome.
How you would counter it:
Since I can't use either a fore mentioned techniques, I would have to avoid being knocked into the air, and if I am, either substitute the attack, or use something that the enemy can't get near, like lightning armor.
How you perform it (with as much detail as you can):
With that I tackle your clone, and we both go off the rampart. As we fall through the air I grab your clones legs and position myself accordingly. Wrapping my legs around your neck and straightening your neck, I hold on to your waist and we build up momentum. As we near the ground I close my eyes and wait for the inevitable crash, or crunch to be more precise... Your clone's head hits the ground and a large thud sound is made. Your clone disappears in the usual *poooof*.