What a fun project!  I have made two journals in this style, and I really like it.  It looks cleaner than a Coptic binding and comes together faster.  I also prefer having a spine.  Most importantly, it lays flat when I am painting!  

I added two loops so I could hold both my fine liner and my waterbrush.  This allows me to pull it out of my pack and I am ready to go.  No need to find my tools.  

In my pocket I have color swatches of my paint colors and a color wheel.  

I really loved this project.  I will certainly be making more of these!