However, probably the most important new feature in 12.10 is perhaps the preview feature in the dash. Right-click on a search result in the dash and a preview screen displays, showing a screen shot and a brief description. If the result is an app, the preview also shows whether the result is installed or not, and gives the options to install or launch it. Similarly, if the result is a shopping item, you can buy it from the preview page.
The main inconvenience of the previews is that they replace the main view of the dash, and you have to repeat the search to see other items afterwards. That means that you want to be very sure before you look at a preview. Either the previews need a Back button, or else they should operate like a mouseover, as a similar feature does in KDE.
Ubuntu 12.10 is not a major release so far as features go. Its main interest lies in the continued evolution of the Unity interface.
For one thing, 12.10 confirms what has been increasingly obvious for the last two releases: the main source of customization in the Unity interface is the dash, especially in the selection of lens and scopes. In many ways, the dash has become Unity's equivalent of the panel with its applets in GNOME 2 -- a feature that users can customize as heavily or as lightly as they choose.
Perhaps any popular desktop needs such a feature, but, considering the lack of customization anywhere else, probably Unity needs such a feature more than most interfaces.
Another noticeable trend in 12.10 is that Unity is starting to strain against the confines of its design. Regardless of anyone's opinion of Unity, its original releases were a model of simplicity, exactly as they were intended to be. But now, all the attention given to the dash is making it a more cluttered place.
The same is true on the launcher. As handy as moving the Workspace icon might be, would this feature even be necessary if Ubuntu hadn't added icons for Ubuntu One, Ubuntu One, and Amazon to the default launcher, moving the Workspace icon lower than ever? The movable Workspace icon seems a makeshift solution to a more fundamental problem.
Similarly, previews would be less clumsy if Unity didn't usually default to full-screen displays. Perhaps, too, previews would not even be necessary if the dash wasn't being used for purposes it didn't originally fulfill, such as replacing the browser or product placement.
In the 12.10 release, Ubuntu seems to be suffering from conflicting purposes. So far, the conflicts are not enough to cripple it. But it will be interesting to see in future releases whether the conflicts become worse, and to what extent the Unity interface can retain its initial simplicity.