What is "Model Validation"? See this MSDN article to learn how the model validation works: How to: Validate Model Data Using DataAnnotations Attributes.
This demo illustrates how user input can be easily validated using a model-based ASP.NET MVC validation approach. DevExpress MVC extensions can be seamlessly integrated into the ASP.NET MVC validation infrastructure.
DevExpress MVC Editors have their own container for displaying validation error messages, which can be enabled via the ShowModelErrors property. This container allows you to manipulate validation messages more flexibly, then via the standard Html.ValidationMessageFor helper. You can control how errors should be displayed within editors by using settings exposed via the editor ValidationSettings property, such as the ErrorDisplayMode.