The document discusses new features in ASP.NET Web Forms 4 that improve client-side development, control over applications, and existing server controls. It introduces more predictable client IDs, routing integration, and enhancements to controls like GridView, ListView, CompareValidator, LinqDataSource and DataPager. The client ID and ViewState mode changes give developers better control, while routing allows customizing the sitemap and new control features make the suite easier to use.