Classic Shell 4 is a major new release for users for Classic Shell 3.6.x and earlier. Here's a more detailed list of the minor new features and changes in Classic Shell 4.0 (including new builds) compared to 3.6.8 besides the major ones Ivo mentioned above:
• When searching a Classic Shell setting, you can right-click on a setting and choose "Locate" and it will show you which tab it is on
• New shortcut in the Start menu to open the Start screen (Windows 8 and above). It even shows the background color of your Start screen!!
• Start menu animations for jumplists and fade animation for All Programs or when beginning search
• Start Menu in Windows 7 style can show All Programs by default if you don't want to see Recent/Frequent programs
• Windows 7 treeview style can show folders first
• New setting for the Windows 7 style Start Menu to control the height of the main menu
• The items in the All Programs tree can be rearranged with drag and drop, just like in the cascading menu
• You can drag and drop website addresses (URLs) from the address bar of all major browsers now into the Start Menu to pin them
• With Classic Start Menu running, the Start Screen will also open using Win key on the correct monitor with the mouse pointer
• Most skin bitmaps (like the user frame) now support masks and can be tinted with the glass color
• In HKLM version of settings, you can add “_Default” to a setting name to override the default value without locking the setting for all users
• You can type “none” for the label of a menu item to keep it blank (previously, "none" was only possible for getting a blank icon)
• To permanently hide a program from the Start Menu's Frequent list, use this "NoStartPage" method: http://support.microsoft.com/kb/284198.
• To permanently hide a Modern app or some new desktop app shortcuts from the MFU list which won't hide with "NoStartPage", use this method: http://msdn.microsoft.com/en-us/library/windows/desktop/dd378459(v=vs.85).aspx
• The search results category headers can be expanded/closed within the menu itself using Enter key or by clicking them. Clicking on the header's text (or Ctrl Enter) opens results in Explorer
• Support for wildcard filtering of paths in the search box e.g. C:\Windows\*.exe or %tmp%\*.log
• Store, PC Settings and other Modern app shortcuts from Programs folder are listed in the Apps folder on Windows 8+
• A new turn off monitor command that you can add to your Shutdown submenu
• File search can search your emails (Windows Mail, Live Mail and Microsoft Outlook) if they are indexed by Windows Search
• Nested settings. Dependent settings are offset from their parent and greyed out if parent setting is disabled
• Computer/This PC item can now show a list of drives as a menu without expanding each drive further
• Secondary Tiles for Modern apps show the personalized tile name and can be launched from the menu as well
• "Install Updates and Shutdown/Restart" functionality like the original Start Menu
• Aero Glass rendering if the MSFN member BigMuscle's AeroGlass for Windows 8 mod is installed
• Enhanced keyboard shortcuts like Home/End/Page Up/Page Down in addition to F2, Del, Alt+Enter etc working everywhere
• Shift+Win uses a hotkey instead of a keyboard hook so it will give less problems and work with elevated programs
• The icons and data are saved to a cache on disk at %APPDATA%\ClassicShell, so the menu should stay responsive all the time. If you don't want repeated writes to the disk such as in case of an SSD, set the Read-only attribute for the %appdata%\ClassicShell\Datacache.db
• Right-click for the Win+X menu works even when all corners are disabled when using the Classic Shell button
• New Start Menu setting for the icon size for the Classic button
• Classic IE9 renamed to Classic IE as it has title bar and status bar enhancements for IE9, IE10, IE11 and future
• The Classic Shell installer and binaries are now digitally signed so you can verify its authenticity and avoid malware which spoofs it
• New Start Menu setting to override the color used by the menu in its glass areas
• Improved support for systems like Nvidia surround and AMD Eyefinity that modify the position of the taskbar
• The Start Button settings are applied live and you can see a preview of the button image in the settings dialog
• The Windows 8.1 setting to skip the Metro screen can be accessed through the Classic Shell settings
• The installer uses better compression that reduces the download size by half
• Language related improvements (See here how to translate Classic Shell: http://www.classicshell.net/forum/viewtopic.php?t=1344&p=6973#p6973)
◦ Country flags in the Languages tab
◦ Language files can be downloaded directly from the settings to %ProgramData%\ClassicShell\Languages
◦ The auto-update checks for new language files
◦ Old language files can be used if newer ones are not available
◦ Currently unsupported languages can be added later
◦ The settings in the skins are localized (and their tooltips)
◦ The names of the menu commands are localized
◦ The Settings dialog has a place to put the name of the translator
• Note: Classic Shell 4.0 no longer supports Windows Vista
• It's FREE!!!
There is also an elaborate feature comparison available now, of Start Menus in case you are undecided whether to go with Classic Shell: http://classicshell.net/forum/viewtopic.php?f=17&t=2399&p=11787
Get a matching Windows 8.1 skin here (you may have to tweak some settings): http://www.classicshell.net/forum/viewtopic.php?f=7&t=1186