Managed extensions for VCL is the best components suite to work with .Net framework from Delphi and C++ Builder.
Managed VCL can:
Create .Net objects without registering them with COM.
Create and use .Net objects that are not COM visible.
Create .Net objects using parametrized constructors.
Call properties/methods/fields of .Net object including static properties/methods/fields.
Handle .Net exceptions and get all .Net exception properties including exception type name, StackTrace etc.
Get information about loaded instance of .Net framework such as memory usage and size of heap by generation.
Managed VCL can not:
Query .Net interface if it is not COM visible.
Work with .Net events.
Work with .Net controls.
Managed VCL will not turn your Delphi or C++ Builder into .Net language and it some other features may not be available.
Managed VCL includes special components for:
ADO.Net - supports almost all ADO.Net features. Components to work with all standard .Net providers (those that are available in .Net framework) are included.
JScript.Net - lets you execute JScript.Net scripts from Delphi/C++ Builder application.