Has anybody used tablet pc type form factor for reading eBooks and esp. PDF papers?
Yes - I've used a convertable tablet pc as a lab notebook replacement and document reader for four years now. Initially this was in a work context but I also quickly adopted it instead of paper for hobbies etc. The key aspect for me was the availablity of Microsoft OneNote which supports note-taking, interlinking and PDF import/annotation.
At work I had to read and review a lot of documents. This application lets me print any document or import a PDF as a OneNote file so I can then mark it up and highlight/edit using the tablet pen. Finally I could publish the result as a PDF and send back to the author. Material can be entered as handwriting and left as-is or converted to text, but either form can be searched for.
A tablet pc also makes a difference in meetings. At work it had got to the point that almost everyone was talking to others while looking down at their keyboards & screens for most of the time. With the tablet I spent more of my time looking at the person I was talking to.
For me the key to note-taking, diagramming etc is a pen interface with the resolution and responsiveness or pen and paper. I find the touch based interfaces completely inadequate for such tasks having tried out my daughter's iPad.
So, while the iPad is of no value to me in this kind of application I hope it will prompt a price reduction and wider range of slate pc's (ie no permanent keyboard) which offer a pen interface of similar resolution and responsiveness as my current device.
BTW I've found the 1024x768 display on the X61 perfectly adequate for the majority of work, the only time I have found the display wanting was for photography where the screen didn't have the level of clarity I needed compared to desktop displays.