Apple originally planned an October release for iTunes 11, but it was held back until November and actually arrived overnight.
The overall design is closer to that of the iTunes Store, with a revised version of the Grid layout as the primary means of displaying the library.
Gone is the left-side pane displaying library folders, playlists and attached devices such as an iPod. Switching between the music library and movies or podcasts is now achieved through a popup menu on the left end of the tab bar, while a connected iPhone/iPod/iPad shows up on the right, next to the iTunes Store button.
Once the iPhone (etc) is attached, music can be added manually by dragging and dropping a song, album or playlist.
A potentially useful feature is 'up next' - a simple way to see which songs are cued up to play and to insert a song at the head of that list.
iTunes' mini-player has also been reworked, making it possible to choose content without returning to the main display. It also incorporates the up next feature.
For those who start watching iTunes movies or TV shows on one device and then switch to another, iTunes' iCloud integration means such content is automatically bookmarked across devices.
While iTunes has the overall greyness we've come to expect from Apple, at least the pop-up menu for switching between content categories such as Music and Podcasts uses coloured icons
iTunes 11 works with OS X 10.6.8 or later, or Windows XP or later (Windows 8 is supported). Download it here or via Software Update.