Very cool, I recently purchased an iPad pro and Pencil and was looking for something like this. I really like the idea of infinite canvas (a la PureRef) for organizing thoughts and references and making relationships between different types of data.

Since you said you're looking for feedback, I'd love to be able to add an Apple or Google Map view, and zoom into a specific area, add pins, and add notes. Think planning a trip or road trip.

The other idea I've been looking for is something that renders in-line web previews in a flexible way. So if I were to paste a link to a website into the app, it wouldn't treat it as just a text hyperlink, but rather, render a small web preview that I could resize or manipulate to display the portion of a page I'm interested in. Ideally this would then be cached so if the page were to update my preview wouldn't break. But also have an option to refresh the preview to update to the latest content. Or auto-refresh to use it more like a dashboard monitoring tool.

Otherwise, for critiques, I wish it played nicer with landscape/portrait. And I kind of like how interactions are geared towards dragging things in from off the screen or flicking things off the screen, but I feel like it's not quite smooth yet. Things seemed to get stacked together and cluttered half in/half out of the canvas as I was working through the tutorial.

Cheers for the launch!