Customizable filtering allowing you to define your own filtering descriptions
Excel-like UI letting users to quickly pick a filter value
RadCarousel
Reflection
ScrollBar visibility
Selection notification events and dependency properties that allow for easier styling
RadCalendar
Date selection
Culture awareness
Different views
Navigation
Customization
Multiple selection
New Controls
Slider
Horizontal/Vertical Orientation
IsMoveToPointEnabled
IsSnapToTickEnabled
NumericUpDown input control
Numeric/Percentage/Currency/Custom Formatting
Advanced navigation
Minimum
Maximum
SmallChange
LargeChange
etc...
UpDown control - uses paired arrow-buttons to increment or decrement a certain value
ProgressBar
Minimum
Maximum
Value
Customizing the appearance via ControlTemplates
PanelBar
Rich events model
Sinlge/Multi ExpandModes
TreeView
Databinding
Drag and Drop
Checkboxes (Tri-state checkboxes)
Keyboard support
Multi-node selection
Single Expand Path
Node editing
Known Issues
High CPU load when using layered windows (Window.AllowsTransparency=True or Window.WindowStyle=None) in your app. This is a Windows/Microsoft .NET issue that will be addressed in .NET 3.5 SP1.