Rated 4 out of 5 stars
I am thinking that this is a good start. It can be more!
I like the instant access to contacts and Add-Ons, but I would like to see a switchable window to include the Folders sidebar. If this could be integrated it would be great. A button to quickly access the side bar sow/hide would also be a great addition.
I would also suggest navigation buttons on the top menu bar of the side bar for quicker access from one window to the next.
This by no means "all-in-one-sidebar" and it was not meant to be, nor should it be modeled in the same fashion.
I like what is happening here, and hopefully more options will be made available as a replacement for the folders sidebar.
I will be watching this Add-On.