My paperium pen has just arrived. I decided on paperium because it's for Mac and does vector graphics. This is an Austrian product so it has that German-quality feel to it like other German art materials and comes in a classy white package (as befits a product for Mac

). The paper is smooth and high quality. It comes with a spiral bound 210x210mm sketch book, and you can buy extra book packs of varying sizes. I got the additional (black) hard-cover A4 book which is also very good quality, like an executive diary except completely blank.
The pen charges via a USB charger, but actually works via bluetooth connection as soon as you pair it up with the computer (after charging the pen). There is a PIN number required for pairing to prevent it working if someone steals it. The registration process is also security-conscious (to the point of being a PITA like Adobe) requiring registering both the pen serial number and software CD code on the paperium website before you can even start to use the paperium app.
There's an add-on for character recognition which looks pretty good, but I didn't get that as I only want this for sketching and doodling. Never having used one of these things before, I am very impressed with this particular one. You can select from a list which file format you want your scribbles to be (jpg, png, pdf, svg etc etc) and simply drag and drop the page onto the desktop or other app to convert it. Very Mac-like dragging my paper scribbles into Illustrator and having them converted instantly into vectors.
Each book/let and each page is unique so if you go back to a page to add more scribbles, the same page on the computer is updated. A feature that I wasn't expecting is that each update is a 'revision' which you can show/hide like layers in photoshop so you can go back in time if you need to, or remove an initial layout sketch if you do a more comprehensive sketch over it.
I highly recommend this product, but both pen and extra paper are relatively expensive so would be difficult to justify for those on a budget if they don't have a specific purpose for it. Sort of like buying a Rotring and art paper. If you just want handwriting recognition or to take notes and scribble diagrams, I'm sure there are cheaper alternatives.
PS. From what I can gather, apparently the pattern on the paper which the pen/software recognises covers a virtual several million square miles or somesuch staggering area without repeating so the pen knows exactly where it is anywhere in that whole area down to the micro mm. Each company which licences these pens buys a small segment of that area to print up, so no two pages are ever the same.