We have gotten a small slew of issues on Android due to rotation. This is primarily caused by us screwing up the templates and forgetting to add a single parameter to the attribute for the main launcher. To fix this open your Activity.cs file in your android project and find the ActivityAttribute. Once you have found it, make sure you pass the following parameter to it:
ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)
This should allow rotation to work as expected in Xamarin.Forms.