Agreed. For note taking at lectures I use onscreen keyboard's handwriting recognition to input text with the pen, but can also swing keyboard around and type as well as inking notes and diagrams. If the lecture has the PowerPoint slides as pdf file, I have that open too and use Send To OneNote or just copy/paste to insert graphs or diagrams.
I use it as a white board while teaching in small groups and even have pages with drawings and diagrams already inserted which I can annotate and use as I teach.
I make shopping lists at home and then open them on iPhone while out shopping to check off what I get.
I've been watching video tutorials on YouTube and keep learning more things you can do with OneNote.
Especially for the Surface, OneNote is Microsoft's killer app.