The user interface is not standard and it's also not very "discoverable".
* The buttons on the lower right should also be on the menu.
* Since they bring up a dialog they should be tagged with ellipses...
* The "Delete..." button should be in a contextual menu as well.
* The control to switch views should be visually distinct from a button, perhaps a labeled arrow.
* The animated rotation for Mac OS Software was surprising: simply having more tabs in the tab bar may have been preferable.
* I still can't figure out how to enable or disable a plugin rather than delete it completely. I would expect this to be a button and a contextual menu.
It looks like it could be a very useful tool, once these quirks are ironed out.