WPF

The Windows Presentation Foundation is Microsofts next generation UI framework to create applications with a rich user experience. It is part of the .NET framework 3.0 and higher.
WPF combines application UIs, 2D graphics, 3D graphics, documents and multimedia into one single framework. Its vector based rendering engine uses hardware acceleration of modern graphic cards. This makes the UI faster, scalable and resolution independent.
The followinig illustration gives you an overview of the main new features of WPF

 

Separation of Appearance and Behavior

WPF separates the appearance of an user interface from its behavior. The appearance is generally specified in the Extensible Application Markup Language (XAML), the behavior is implemented in a managed programming language like C# or Visual Basic. The two parts are tied together by databinding, events and commands. The separation of appearance and behavior brings the following benefits:

• Appearance and behaviour are loosely coupled
• Designers and developers can work on separate models.
• Graphical design tools can work on simple XML documents instead of parsing code.

Rich composition

Controls in WPF are extremely composable. You can define almost any type of controls as content of another. Although these flexibility sounds horrible to designers, its a very powerful feature if you use it appropriate. Put an image into a button to create an image button, or put a list of videos into a combobox to choose a video file.

 <Button>
    <StackPanel Orientation="Horizontal">
        <Image Source="speaker.png" Stretch="Uniform"/>
        <TextBlock Text="Play Sound" />
    </StackPanel>
</Button>

Highly customizable

Because of the strict separation of appearance and behavior you can easily change the look of a control. The concept of styles let you skin controls almost like CSS in HTML. Templates let you replace the entire appearance of a control.
The following example shows an default WPF button and a customized button.

Resolution independence

All measures in WPF are logical units - not pixels. A logical unit is a 1/96 of an inch. If you increase the resolution of your screen, the user interface stays the same size - it just gets crispier. Since WPF builds on a vector based rendering engine it's incredibly easy to build scaleable user interfaces.

WPF advantages

• It's newer and thereby more in tune with current standards
• Microsoft is using it for a lot of new applications, e.g. Visual Studio
• It's more flexible, so you can do more things without having to write or buy new controls
• When you do need to use 3rd party controls, the developers of these controls will likely be more focused on WPF because it's newer
• XAML makes it easy to create and edit your GUI, and allows the work to be split between a designer (XAML) and a programmer (C#, VB.NET etc.)
• Databinding, which allows you to get a more clean separation of data and layout
• Uses hardware acceleration for drawing the GUI, for better performance
• It allows you to make user interfaces for both Windows applications and web applications (Silverlight/XBAP)

WinForms advantages

• It's older and thereby more tried and tested
• There are already a lot of 3rd party controls that you can buy or get for free
• The designer in Visual Studio is still, as of writing, better for WinForms than for WPF, where you will have to do more of the work yourself with WPF