The following are the benefits of using ADO.NET in .NET 4.0 are as follows:

1. Language-Integrated Query (LINQ) - Adds native data-querying capabilities to .NET languages by using a syntax similar to that of SQL. This means that LINQ simplifies querying by eliminating the need to use a separate query language. LINQ is an innovative technology that was introduced in .NET Framework 3.5.
2. LINQ to DataSet - Allows you to implement LINQ queries for disconnected data stored in a dataset. LINQ to DataSet enables you to query data that is cached in a DataSet object. DataSet objects allow you to use a copy of the data stored in the tables of a database, without actually getting connected to the database.
3. LINQ to SQL - Allows you to create queries for data stored in SQL server database in your .NET application. You can use the LINQ to SQL technology to translate a query into a SQL query and then use it to retrieve or manipulate data contained in tables of an SQL Server database. LINQ to SQL supports all the key functions that you like to perform while working with SQL, that is, you can insert, update, and delete information from a table.
4. SqlClient Support for SQL Server 2008 - Specifies that with the starting of .NET Framework version 3.5 Service Pack (SP) 1, .NET Framework Data Provider for SQL Server (System.Data.SqlClient namespace) includes all the new features that make it fully compatible with SQL Server 2008 Database Engine.
5. ADO.NET Data Platform - Specifies that with the release of .NET Framework 3.5 Service Pack (SP) 1, an Entity Framework 3.5 was introduced that provides a set of Entity Data Model (EDM) functions. These functions are supported by all the data providers; thereby, reducing the amount of coding and maintenance in your application. In .NET Framework 4.0, many new functions, such as string, aggregate, mathematical, and date/time functions have been added.