In SQL Server Integration Services (SSIS) the DataReader Source component is analogous to ADO.NET's DataReader classes.  It retrieves a Binary Large Object (BLOB) stream from the data source and is therefore efficient and the least expensive option in terms of memory.  Having said that, there are times when it is convenient to convert the returned BlobColumn into a string object.  Within a script component, the following will build a binary array from the BLOB stream and then encode the binary array to a Unicode string.

Dim result As String = _
System.Text.Encoding.Unicode.GetString(Row.FieldName.GetBlobData(0, CInt(Row.FieldName.Length)))

Again, one should be cautious when doing this.  It is similar to using the DataAdapter class to convert a DataReader to a DataSet, so depending on the size of the data, this may or may not be a good idea.