It's a cool idea, but I can imagine people tapping their notes on accident and replaying the audio in class.  I have a tablet laptop, and although I don't really use the tablet feature for in class (unless its a special circumstance; I normally do photo editing and brushing with tablet), I just find typing the notes so much easier and faster.  Not to mention with that pen you can only use their paper, buy their ink, and use their software to share it.

I think if you're a student, like writing notes, and don't already have a portable laptop, this is a good option if it does perform as well as it claims.