I like your goal "to make 'blogging' more expressive and visual, possibly to break a piece off and reboot it, now that it's fallen out of fashion." I have the impression that, with some of your other projects, Kicks, you are trying to do this for all the web, not just blogging.

However, for my taste, this feels a little too close to Tumblr, which I don't think achieves "expressive and visual" in a deep sense. I hope that you will continue to explore and find more ways to differentiate yourself.

Misc. feedback:

I like how you present small blocks of text, but large blocks of text seem cramped sometimes, difficult to read.

The backgrounds are killing me. Perhaps, each background could have a solid-color fallback and readers could toggle to only display the solid fallbacks?

"Composed on today" -> "Composed today" (likewise for "yesterday")

I hope this doesn't come across as negative. What you're doing is very interesting to me and I look forward to seeing where it goes. It just hasn't fully achieved your stated goal, yet, in my opinion.