It is working as described, and i have a few suggestion.
1. When activated, it shows a very log list of theme (all network activated themes, I have 107), which grossly limits the usefulness of this feature from point of look and feel of site. I suggest there should be an option to limit number of themes to be displayed on the front end.
2. let admin group the themes into bundle, so that they can be offered to site users. I would like to group for example 3 column themes together, another bundle of themes for photoblogs, still another bundle of themes with fluid width width etc.
3. let user select what themes they want to show in frontend for switching.
All these feature would make it very versatile.