Get a piece of paper or cardboard and cut it to 93.6 x 56.2 mm (3.7 x 2.2 inches). That's the size of the screen
Can you visualize yourself using that screen for taking notes? Maybe write some words on it to see how small you can make them so they're still comfortable to read; can you get enough on the "screen" at that size to make it worth typing?
If yes, you can comfortably do so, then the Pandora might be excellent for you. While the Pandora's keypad is too small for touch typing, I can achieve almost 50 wpm on cell phone's QWERTY thumbpad and it's even smaller than the Pandora's. With practice, I don't suspect the thumbpad will be as great a hinderance as some would suggest.
On the other hand, there are portable fold up/roll up keyboards to be had for $20-$30 that are excellent for touch typing and just as easy to carry as the Pandora.
I can speak from first hand experience: I used an old Palm III and a fold up keyboard for taking notes when I attended university and it was a godsend! All course material was usually available via PDF, so I was able to download slides and text for the day onto it, such that when I went to class that's all I took: palm pilot in one pocket, keyboard in the other. At the end of class, while my classmates were struggling with getting text books and binders and loose sheets into backpacks, I'd just put on my jacket and walk out the door. Good times.
If I had had a Pandora back then, it would have been even better!