property of RadEditor returns editor content as pure text. It does convert <BR/> tags into \n lines correctly - so, if you later load the editor content in a textarea, it will display those new lines correctly.
However, since you load content back into the editor, of course, there is a problem. "\n" symbols mean nothing in HTML - they are simply ignored by the browser. So, to display content in several lines, you should use code such as
editor1.Content = dbContent.Replace("\n", "<br/>");
the Telerik team