Apart from "cool", is there a tangible advantage to this over a pad of paper? I don't see one. It looks to me like a future expensive thing I forgot on the bus. I'd also for sure lose the pen and end up using it to support real paper to write on.
Now, if you could do things like zoom, copy/paste, and connect (wifi) with a computer/projector, I could see buying one.
I've wanted one for a while. As a student, I take notes all day long. Digitizing them by hand is a pain, but if they were immediately put into digital format, that would be great. I could carry around years of notes on a flash drive, conveniently organized by subject. With a little work, you can even add keywords/subject searchability to notes.
Currently, I could take notes on a laptop, but in mathematics this is extremely difficult (you have to be very very fast with LaTeX), and realtime diagram entering/editing is basically impossible with a laptop.
Now, if you could do things like zoom, copy/paste, and connect (wifi) with a computer/projector, I could see buying one.