I love what you've created for functionality. I loath the left navigation. No-one can remember what icons are for quickly, the eyes have to rollover an icon, look up to the next column heading, and down to the subheading pages.
Far better would be just following the standard convention for all other Apps and just having a single 2-level navigation. You've created a 3-level navigation that just doesn't need to be for so few pages to visit. Having all visible in one column and a scrollbar would be so much faster to navigate and not feel annoyance at the navigation every time I have to re-try to find something.
Sorry, I like everything else. This really needs to be more user-friendly.