This is the latest work from mathematical-coffee (I think her name is Amy -not totally sure), the extension was ported to GNOME 3.8 two months ago, and it had an update last month.
What it does, is to transform the workspaces thumbnails list on the right, to a much more useful grid, but with the cost of horizontal space for thumbnails windows in overview.
Grid Extension with 5 windows open, illustrates that the horizontal space waste, isn’t too bad
Left/Right Navigation Similar to GNOME 2!
One thing I missed in GNOME 3, was the ability to arrange workspaces into square. With that extension you can use <Ctrl+Alt> + Up/Down/Left/Right arrows to navigate through workspaces and even <Ctrl+Alt+Shift> + Up/Down/Left/Right to move focused window in another workspace.
Workspace-Grid Extension has and a set of nice options. Basically is one of the most completed extensions and in my opinion it does it better from default Shell behavior. However it is hard to adopt to it, once you get used to the simple workspace list that Shell offers.
- Extension page => https://bitbucket.org/mathematicalcoffee/workspace-grid-gnome-shell-extension
- GNOME 3.8 Installation => https://extensions.gnome.org/extension/484/workspace-grid/