Yes it's an instantaneous response making it simpler than deciphering all the data in a spectrum analyzer.
As to how you use it that will depend on who's school you subscribe to and not in the formal sense and no pun intended. Brian teaches his methods at the Galloup school using a fixture and they are not "free plates" but again in a fixture.
Ervin Smogyi is also a fixture guy and for those who attended Ervin's classes and maybe got to sleep in the Brazilian Rosewood room when staying there you will have learned a different method.
Lots of us were or are "free plate" tuners where the plate is not in a fixture and held on various nodes to isolate variables and we of course have our own methods.
It's a tool for sure and although some hobbyists might buy it and employ it anyway the price is steep for folks who don't work OR participate in the trade commercially.
But if I was still building the price is mouse nuts compared to what we would get for our guitars and I would most certainly have one and be looking to up my game with more control and certainty over how my wares ring.
On the Looth Group lots of the guys (meaning men and woman) have bought 3D printers and with me NOT being on board our shop bought one too. We spent maybe 2 - 3K on ours a Bamboo. Dave was all over it initially but I was a buzz kill and could not understand what the dang thing will do for us that we can't do already AND how long it will take to amortize it's cost by billing something that it produces.
Ours sits pretty much unused now after Dave printed all the cool tools that others on the Looth group spent hours and hours creating the code for. I have Gluck Puck on my bench with is a string keeper for vintage Fender style head stocks.
But I worked for two decades without a Gluck Puck and now at my age I can't remember that I even have one to ever use....
Going back to the hammer it has the potential to directly improve every instrument one makes. I said potential. What you do with it is of course up to you.
My bet is it will take off and today's $450 is only 1/6th of the cost of our Bamboo space taker upper.....
At the very least this tool would easily guide one through avoiding wolf notes by intentionally creating some mismatch in the natural resonating frequencies of the top and back. That alone is pretty important and useful especially for builders who do not tune their plates.