I've been using Good Notes for university and life in general for two years now, and there are several features that would make the app a much better place to study.
I've thought about them and here they go (my native language isn't english so sorry if i make mistakes):

-The audio option could be better (it would be great to be able to leave them inserted as stickers in any part of the sheet and thus divide the audio into sections, and that when pressed the previously recorded audio would sound). Also give them names and that they are not predetermined as "audio clip". Each audio clip can be paused and continue recording within the same clip, otherwise it is messed up. Being able to increase their speed.

-Choose the background color, you can only choose between white, beige and dark grey, although one could paint the entire sheet, it is not the same since there are no lines to guide oneself, and if I draw on top with another color, when moving the drawing also moves the background.

-Being able to set objects, there is only the option to set things according to categories (text boxes, handwriting, etc.) there is not the option to set something specific. For example, if you want to move a single image but not the others.

-Put videos, in the same way as audios.

-To be able to make animations, that there would be a function such as "start animation", you draw with the pencil and then "end animation" and what you did remains as a gif that can be reproduced with a click (I study astrophysics and this would help me, for example , to model a trajectory that I find difficult to visualize in a static drawing).

-To be able to edit the opacity of the objects, for example if I have an image but I want it to look more transparent because I want to write on top of it. To this could also be added that there was a mini photo editor for the images that are inserted, sometimes I take the photo from good notes and insert it right away, but I don't like how it looks, this could include colors, perspective, stretching, etc. .

-Add justified text option.

-The color and design of the folders could be customizable, as well as the background of the main menu and the interface in general.

-The text could be erased as if it were written with a pencil and move in the same way and not as a whole, it would be much more comfortable.

-Automatic backup option.

-Add the option of tracing with a dotted line and perhaps other formats.

-More pencil textures.

-Add line option with gradient effect or things like that.

-More cropping options, not only square and freehand, but also circular and/or automatic object recognition.

-Move things directly from one sheet to another with the pen, without having to copy and paste. This is useful for vertical scrolling mode.

-When I export the documents as PDF or JPG, the highlighted colors appear darker.

-Sometimes the text appears double when trying to move it.

-When writing in the app, the color of the highlights is not very powerful, but if I highlight something and erase a little bit of the highlight with the eraser, the color of the highlight changes to a more powerful one.

-When highlighting, what is written becomes opaque and so that it doesn't look like that I have to do the process in reverse: first highlight and then write the text on top of it, this is uncomfortable because one does not measure the size of what is going to be highlighted well with advance. By default the highlighter should be behind the writing and text.

-That the zoom out in the vertical scrolling mode, have the distance limit where the sheets occupy the screen size, as it happens with the zoom out with the horizontal scrolling mode.

-Tabs with subcategories, that is, having tabs within another tab, being able to group them.

I suggest you look at the reviews that people write in the App Store, it is full of suggestions and errors to improve.
:)

PS: Just for fun I attach a screenshot of the Schrödinger equation summary i made with GoodNotes.

Thank you! I love the app.