The text can be used to show why the application is busy. Available in the R2 2018 release.
Using the code code below, the RadBusyIndicator will animate the first time you toggle IsBusy.
However, any subsequent changes to IsBusy will show the AnimationType's graphic, but without animation.
<telerikBusyIndicator:RadBusyIndicator x:Name="radBusyIndicator"
AnimationType="Animation4"
IsBusy="{Binding IsBusy}"
IsVisible="{Binding IsBusy}"
Grid.RowSpan="3" />