I appreciate aesthetics as long as they are done in moderation and don't impact the readability of the book. I read because I love to read, and so I don't feel like I need the book itself to be embellished to keep or hold my interest. I'm going to read the book either way. I do get wary when I see books that have a lot of artsy touches on the pages, because I feel like I want the writing to speak for itself and not rely on these types of things to create the aesthetic or mood of the story.

That being said, minor things like small designs around the chapter titles, the font choice, even the font color, etc., are things I do appreciate in novels when done in moderation. Even beautiful jackets on hardcovers, or engraved designs on the hardcover itself are great. They aren't on every page, and don't impact readability. I think more gratuitous artistic choices are great in poetry, and one of my favorite collections has artwork all up and down the pages and worked through the poems themselves.

It sounds like in your friend's case, the aesthetic aspect might be a little overdone for the average reader. I think it's great you have come to like it and can see how it reflects who they are, but I'm not sure if this message will be communicated as well to the average reader who hasn't met your friend and doesn't know them. To them, the style might come off as confusing or distracting and they might miss how the style is a reflection of the author's personality.