I'm seeing the same behavior as HaoleKai - I have icons set to small and no text.
I tried eliminating the toolbar altogether, but I couldn't figure out how to do some things with only the menu bar. For example, if I'm connected to iTunes, I can see the library by clicking on the device menu item and selecting "show contents of main memory" or something like that. Normally, I would click on the Library icon in the toolbar to get back to see the contents of the Calibre library, but that doesn't work with the menubar option - I get the normal pulldown about switching libraries which isn't what I want to do. I think the library menubar item needs a "show books in main calibre library option".