Having watched the most recent development stream, I couldn't help but notice the lack of pages in the spell book when they were explaining the Direlord spells. Having a scroll bar in a spell book just seems incredibly odd, and I'm hoping this isn't the format they've decided to go with as it functions more like a digital tablet than a physical book. Only having space to display five spells on the left-hand-side of the book at any given time seems quite restrictive, too.
Also, maybe it's just me but, that sound effect when they're casting spells (heals, I think, not the battle meditation) really bothered me, I don't know why, it just didn't seem right. Maybe it's just a subjective thing?
They had a book UI shown in the past but they recently changed a few things with the spell list such as the way the Mastery sytem works with it and now theres no lower versions of the same spell.
Unsure though if the book is gone or simply being re-tolled for the current build of the system, I'm hoping that it comes back in some way.
The UI, like most of what you saw in the world is greyboxed for testing so they can easily make changes to it when things break or people poke holes in their ideas. Once the tabbed pages are ironed out for what is displayed and what they want to show the players they add in the fluff to make it look nice. Its the same with inventory and everything else. Once they settle on a format and size they will build the art to match it.