I had one for a couple weeks right about a year ago. I was very impressed by its ability to mimic paper. Unfortunately, it didn't do much more than mimic paper, so I sold it and bought some nice notebooks.
However, I think that was before the software projects mentioned in this post. I never tried to SSH into it, so maybe it's possible to use it for things that you can't replace with paper.
I mean, this is like saying a Kindle isn't worth it because you can only read books on it. Sure, if you don't value the fact that it is digital (almost inifite capacity, delete without making a mess, backup to computer, send PDFs of the notes that you created, etc.) it's "not more than a notebook" but then you really missed the point of the device...
It goes a little farther than just mimicking paper. Being able to rearranged my notes notes just by dragging and dropping was the killer feature for me.
However, I think that was before the software projects mentioned in this post. I never tried to SSH into it, so maybe it's possible to use it for things that you can't replace with paper.