5) Less Obtrusive Notifications: One of the most annoying aspects of many modern desktops, both proprietary and free, is the seemingly endless parade of notifications demanding your attention. KDE at least lets you control which notifications display, but in many cases they are either irrelevant or an interruption your work that does not need immediate attention. GNOME 3 appears to have no fewer notifications than the norm, but they sit quietly at the bottom of the workspace, where they are unlikely to be obscured by open windows, and can be read or dealt with later as you prefer.
6) Improved Display of Virtual Workspaces: On the right of the Activities overview is a visual display of all open workspaces that shows the applications running in each. This is a marked improvement over earlier GNOME releases, in which workspaces were visible only as a small cluster of rectangles in the panel, and the listing of panel contents was restricted to a text list.
7) Increased Emphasis on Advanced Features: This is both the greatest advantage of GNOME 3 and the one most likely to be resisted. However, GNOME 3 makes several advanced features more obvious and easier to use. The Dash on the Activities overview displays Favorites more prominently, while the switching between screens encourages the learning of keyboard shortcuts.
Like the use of styles in a word processor, these features make GNOME 3 slightly harder to learn, but, once you learn them, lets you work more efficiently. By contrast, those who have the hardest time with GNOME 3, I suspect, are those who rely entirely on the mouse for switching between screens and workspaces.
Like any major change, GNOME 3 risks being rejected simply because it is different. Perhaps it will turn out not to be suitable for your work habits, but that is a decision that you should take several days, if not weeks, to decide. If you do decide against using it, here are some of the possible reasons:
1) The Need for Hardware Acceleration: Adam Williamson informs me that testing convinced GNOME developers that the time had come for a desktop that required basic 3-D video support.
However, for some users, that is still only possible with proprietary drivers, which they either choose not to use or else cannot easily find because their distribution's repositories do not carry them. In such cases, the fallback mode is available. But, since that is a stripped down version of the GNOME 2 series' desktop, there is not much incentive to use it except through necessity. Many users may prefer to look for alternative desktops.
2) No Icons on the Desktop: Depending on the distribution, GNOME 3 may not allow icons on the desktop. For maybe half of users, that will be irrelevant, but for the other half, this limitation will be a deal-breaker. Unless they can learn to edit Gconf -- and, so far, I haven't found any instructions on the web -- they will either have to learn to live without icons or else hunt for a new distribution.
3) Apps Only Open One at a Time: To open applications, you have to switch to the Activities screen. Selecting an application immediately switches you to the workspace, which means that you have to switch back to the Activities page to open any application that you want to run at the same time as the first. This limitation also exists in the classic menu of the GNOME 2 series, but it requires far more mouse clicks (and therefore delay) in GNOME 3.
4) Lack of Continuity Between Overview and Workspace Window Placement: One of the best features of the Activities Overview is that it displays the windows open in a workspace so that you can see all of them. Unfortunately, if you zoom in to the workspace, that view is not maintained, and the windows are in whatever order you left them in. This is both disconcerting and inconvenient. I suspect that many users would appreciate the option for the arrangement of windows in the overview to be carried over to the workspace.