Text is a common source of frustration in Revit. Replacing, improving the text editor remains a top rated wishlist item. Jean-Marc wrote to me the other day to mention something that I can assign to the Dept. of Subtle. If you use Bold and Underline on a portion of text and then transition to normal but still underlined Revit text doesn't deal with the underline transition well. Here's a comparison between what happens in Revit and Word.
I don't often use text but when I do I'm always wishing for that new text editor.