"Is the artbook worth it?" - take a look for yourself.

...because you can read it online here: https://readcomiconline.li/Comic/The-Legend-of-Zelda-Breath-of-the-Wild-Creating-A-Champion

Personally I think it is worth it for the background information and concept art alone. For example, I would have NEVER guessed that this random weird pic here is official concept art from when they first played around with the idea of a motorbike:

No joke.

Obviously, they rejected the idea ... at first. The idea of a bike was later brought up again for the second DLC and ended up becoming the Master Cycle Zero, albeit with a lot more "sheika-esque" design.