This thread has now been closed to direct all further updates about this release onto the new Stable release announcement:
This is a combined bugfix and feature release:
If you find any new issues in this release compared to the current Stable versions, please do file a quick bug report, and then feel free to add a note on this thread with the bug number. Thanks!
You can downgrade back to the current Stable version by switching updater channels.
Release Blog including estimated timeline to Stable: https://releases.xamarin.com/beta-release-ios-9-1-xcode-7-1-support-el-capitan-fixes/
[iOS] Xamarin.iOS 9.1 (and XamarinVS 3.11.1585) now require Xcode 7 or higher, and consequently also OS X 10.10.5 or higher.
[iOS] This version does not provide support for tvOS or watchOS in this release. Xamarin has previews (XI 9.3) available for both platforms. See the corresponding preview release thread for the latest information and download links.
Bug 31369 - [Mono] Only affects Desktop Mono: programs that use the APIs in
System.CodeDom.Compiler to compile code dynamically will fail with "System.SystemException: Error running mcs: Cannot find the specified file" or "System.SystemException: Error running vbnc: Cannot find the specified file".
Bug 35231 - [iOS] "error CS0101: The namespace `UnifiedIosBindingProject1' already contains a definition for ..." when attempting to use
enum types in binding projects due to the new
enum behavior. Temporary workaround: Move the
StructsAndEnums.cs file to a separate small iOS class library project, set the build action of the file to "Compile", and then reference that class library project from the binding project. (See the bug report for additional discussion of this issue and how it might change before Xamarin.iOS 9.1 Stable.)
Bug 35320 - [iOS] [Xamarin Studio] "iPad Pro" is not listed in the simulators menu in Xamarin Studio.
The remaining known issues from older release threads ("Android M Support", "iOS 9 Support – Service Release 1", "Cycle 5 – Service Release 4", and earlier) are unchanged.
EDIT Oct 24: Add iOS bug 35231.
EDIT Oct 26: Update bug-filing links for more precise bookkeeping.
EDIT Oct 27: Add Xamarin Studio Bug 35320.