I really like how the spell book seen in latest game play looks like together with the inventory. However I have some suggestion regarding the spell book which I hope you can look into when you have some time over. I know you are far from finished.
1) I would like to be able to quickly go to certain pages in spell book. Buttons (attached below the book) to either go forward/backward pages: First page, 5 pages forward/backward, 20 pages forward/backward, Last page
2) Be able to either sort between Levels/Names/Type of spells in Ascending/Descending order with 2 clicks bottom of book (small toggles).
3) Filter buttons or tabs (attached to right edge of book) similar to Heroes of Might and Magic spell book but better: Filter buttons which also suits for the class (sorted as described as in 2).
Example EQ necromancer:
DD tab, DoT tab, Snare tab, Fear tab, Summon tab, Buffs tab, Utility tab, Other tab
4) Top of book informs you about the filter + status you are currently using for the spell book. The page number should of course always be showned.
Example 1:
Level 3, levels, asc Which means Level 3 spells are showned, sorted by levels in ascending order
Example 2:
DD, names, desc Which means Direct Damage Spells are showned, sorted by names in descending order
5) Be able to set how many spells you want to see on each page (with one click on toggle buttons bottom of book).
2 spells per page with visible description
4 spells per page. One spell per row with name of spell and type of spell (DoT, Healing, DD, etc). If you however cursor over icon you will see more detailed info.
8-12 spells per page (as in old EQ). Only spell icon with name shows. If you hower cursor above icon you will see description.
Skills too - not just spells. (Anything that there's more than a few "pages" of, need this).
That said, if you only have about a dozen or so spells that are actually used, there's no need. - by that, I mean, that if at level 50, you've accumulated 100 spells, but 80 of them are "old" versions, the only thing you need is something like "move all these elsewhere" (leaving the 20 or so that you use in the first few pages).