Since I was getting ready to move, and wanted to stay plugged into the 'net when I shut down my DSL service... I had to get a mobile phone capable of 4G and wireless hotspot...
...So I started doing some homework a few months back. N-Trig Duosense and the newer Wacom technology that seems to be taking over for their 'Penabled' technology caught my immediate attention. Both are pretty good technologies, but price point left me out of the 10" and 7" tablet form factors (i.e. couldn't persuade the wife that I 'needed' them...). Then I ran across the Samsung Galaxy Note while reading about the new Wacom technology hitting the high end tablet market. Right now I think the HP Slate is the only 10" tablet with it, and a Galaxy 10.1 is in the works (EDIT added after writing: http://reviews.cnet.com/2300-13970_7-10011430-1.html the Tablet will have a digitizer pen with an eraser!)... But, the 5" (5.03") Galaxy Note is a fusion of phone and tablet...
Its a bit bigger than the iPhone/iPod, which is good for sketching. You have an honest Index Card card size screen. Its a bit weird as a phone, and doesn't fit in the pocket as easily... But, it can go far more easily in my cargo pocket then a 10" or 7" tablet. That, and the Wacom based S-Pen in the optional S-Pen Holder kit is pretty slick! Well worth the extra $50.
Compared to small moleskin (storyboard) book:
In the middle of an iPod Touch and Kindle Fire:
A quick scribble with Sketchbook Pro Mobile:
Being a 5" form factor I never rest my hand on the screen. However, thats not too much of a factor so long as the digitizer is touching the screen... However, in spite of being Wacom built... There is no pressure sensitivity in the nib. Being Wacom, there is no battery in the pen reducing the price point compared to the N-Trig Duosense based pens. My pen holder cost about $50 and came with an extra S-Pen. Replacements cost about $40 (or less from some sources, Amazon for example). N-Trig would charge about $80 and requires AAAA or some other insane battery that Radio Shack might carry (slight exaggeration there).
So, while this isn't going to be a true digital sketchbook... It might be worth getting instead of an iPhone. It costs less, and frankly is capable of more with the S-Pen (and I don't recall the iPhone providing you with the ability to set up a wireless hotspot for your computers to access 4G Internet... I could be wrong, I've kinda ignored the iPhone for a while...).