GoodNotes does a hell of a lot more than the stuff I’ve listed above, but those are the features that grab me most, and make me most grateful for the app. It’s magic notebook tech, and turns the iPad into the big Moleskine that trees couldn’t provide.
I personally am not a fan of GoodNotes, but this is one of the better write ups on the app. Also, that zoom feature is in a few other apps including: Notability, and my personal favorite Noteshelf.
I’ve been testing small EDC pens and thus been using paper of late — all I can say is how much better notes with an Apple Pencil and iPad truly are.