Not bad!

Not too bad but all you can do is based on Apple products for game or production software.
You have a better opportunity to offer features like:
A document section to add description details.

Scribbling text is very sloppy, nice to have a text function with the draw functions.

Zoom function with the draw functions.

When you tap on the pen or other function, the options disappear to quick.
May I suggest that you have it so they have to click on the object again to close the tool.

Hope this was helpful.

tungstenreaper about Marvel - Design and Prototype, v4.5