There is a Nuget library called CredentialManagement that wraps the Windows Credential Management API that supports both the old and the new style of UI http://nuget.org/packages/CredentialManagement/
works perfectly
var cm = new Credential();
cm.Target = "mycredentialname";
if (!cm.Exists())
{
Console.WriteLine("cm is null");
}
cm.Load();
Console.WriteLine("Password: " + cm.Password);
Console.WriteLine("Username: " + cm.Username);