You can make a fresh portable install in a separate folder for testing purposes, instead of overwriting your existing 0.9.x installation - no changes will be made to your existing install or to your configuration.
Configuration of individual components is now stored in separate files. Reading of old configuration files is still supported so your settings will be preserved while upgrading from older versions; however you will not be able to downgrade back to older 0.9.x releases without losing your settings.
Some of existing third party components provide functionality that is now provided out-of-the-box. It is strongly recommend to remove these components as many of them are known to have major stability issues. The installer will prompt you whether you want relevant components to be removed automatically.
Components built with buggy foobar2000 SDKs older than 2006-07-30 are no longer loaded. The installer will forcefully remove such components. You will be prompted so you can make a backup copy before proceeding if you intend to keep these files.
To prevent people from running outdated beta versions, every beta version now expires after four weeks from the original release.
A new Context Menu structure has been introduced along with a reworked context menu preferences page.
Holding down shift while opening a menu - with both context and main menu - will bring up menu commands that are normally hidden, so you no longer need to go through the preferences page to access obscure commands that are hidden by default.
Various standard Preferences pages have been reworked. The Preferences dialog now has OK, Apply and Cancel buttons. Existing components need to be updated to utilize the new Preferences functionality.
With Default User Interface, the Edit Menu commands operate on currently selected items, not just on the currently active playlist. This allows - for an example - to use the Copy command on Album List selection.
This feature currently does not work with third party user interfaces - Edit Menu commands operate on the active playlist just like in old foobar2000 versions; relevant components will need to be updated to comply.
You can now set custom filename patterns and paths for front cover, back cover, artist and disc artwork. You also have the ability to set a stub image for each of these.
Buggy third party components are no longer required to play ASX/MMS/RTSP streams. It's recommended to uninstall relevant components.