<p>What issues or refactoring did you have to do when you upgraded from ASP.NET MVC Preview 5 to the newly released <a href="http://www.microsoft.com/downloads/details.aspx?familyid=a24d1e00-cd35-4f66-baa0-2362bdde0766&amp;displaylang=en&amp;tm" rel="nofollow noreferrer">Beta</a> version?</p>

I'm about to do this myself.  Here's the list of changes from the readme:
Changes Made Between CodePlex Preview 5 and Beta
Changed the default validation messages to be more end-user friendly.
Renamed CompositeViewEngine to AutoViewEngine.
Added a Url property to Controller of type UrlHelper. This makes it convenient to generate routing-based URLs from within a controller.
Added the ActionNameSelectorAttribute abstract base class, which serves as the base type for ActionNameAttribute. By inheriting from this base attribute class, you can create custom attributes that participate in action selection by name.
Added a new ReleaseView method to IViewEngine that allows custom view engines to be notified when a view is done rendering. This is useful for cleanup or for view-pooling scenarios.
Renamed the ControllerBuilder method DisposeController to ReleaseController to fit with the pattern that is established for view engines.
Removed most of the methods on the HtmlHelper class, converting them to extension methods of the HtmlHelper class instead. These methods exist in a new namespace (System.Web.Mvc.Html). If you are migrating from Preview 5, you must add the following element to the namespaces section of the Web.config file:
```
<add namespace="System.Web.Mvc.Html"/>
```
This makes it possible for you to completely replace our helper methods with your own.
Changed the default model binder (DefaultModelBinder) to handle complex types. The IModelBinder interface has also been changed to accept a single parameter of type ModelBindingContext.
Added a new HttpVerbs enumeration that contains the most commonly used HTTP verbs (GET, POST, PUT, DELETE, HEAD). Also added a constructor overload to AcceptVerbsAttribute that accepts the enumeration. The enumerated values can be combined. Because it is possible to respond to HTTP verbs that are not included in the enumeration, the AcceptVerbsAttribute retains the constructor that accepts an array of strings as a parameter.  For example, the following snippet shows an action method that can respond to both POST and PUT requests.
```
```
[AcceptVerbs(HttpVerbs.Post | HttpVerbs.Put)]  
public ActionResult Update() {...
}
```
```
Modified the RadioButton helper method to ensure that every overload accepts a value. Because radio buttons are used to specify a choice from a set of possible values, specifying a value for a radio button is necessary.
Made modifications and fixes to the default project template. This includes moving script files to a new Scripts folder. The default template uses the ModelState class to report validation errors.
Changed action-method selection. If two action methods match a request, but only one of those has an attribute that derives from ActionMethodSelectorAttribute that matches the request, that action is invoked. In earlier releases, this scenario resulted in an exception. 
For example, the following two action methods are in the same controller:
```
```
public ActionResult Edit() {  
  //...  
}  

[AcceptVerbs(HttpVerbs.Post)]  
public ActionResult Edit(FormCollection form) {  
  //...
}
```
```
In Preview 5, a POST request for the Edit action would cause an exception, because two methods match the request. In the Beta, precedence is given to the method that matches the current request via the AcceptVerb attribute. In this example, the first method will handle any non-POST requests for the Edit action.
Added an overload for the ViewDataDictionary.Eval method that accepts a format string.
Removed the ViewName property from the ViewContext class.
Added an IValueProvider interface for value providers, along with a default implementation, DefaultValueProvider. Value providers supply values that are used by the model binders when binding to a model object. The UpdateModel method of the Controller class has been updated to allow you to specify a custom value provider.