MS Word's HTML editor is built right into MS Word. No conversion, no "save as", no switching to an extension. The change in the button bar is the only difference from the Word editor.
An HTML template is provided in Word's template library. Conversion of a text file consists of inserting the text file into the template. Tags can be user defined, although the defaults are usually acceptable.
The HTML editor will tag text at a click of the mouse. Tedious end-of-tags are done automatically. Title, head material, and other HTML mark-up are available and generally not too difficult to insert.
But watch out. Microsoft, in it's unsurpassed ego, inserts META tags that indicate Microsoft as the author of the piece and show the description as Microsoft Word. Other essential META tags, such as keywords and descriptions that are so vital to being "found" by search engine bots, can be added to the META tags manually.
This default META can probably be changed in set-up or by some other method, but it's annoying. A lot of pages remain unchanged, even on major sites. Check out the "view source".
Word's greatest value is as a conversion utility. It's capabilities to search and replace RTF text or tagged Ventura Publisher files expedites converting conventional publications to HTML format. For instance, a Ventura @subhead = tag can be globally searched and replaced with HTML tag, <H2>, including the end tag </H2> in one step. If the Ventura text file is saved as an RTF format, Word will convert any font changes to the appropriate <STRONG>, <B>, <EM>, <I>, including the end tags </STRONG>. Very handy.
One of the most useful applications is conversion of OCR (Optical Character Recognition) files to HTML if the OCR files are saved as RTF. Font tags in RTF are converted to HTML font tags automatically and consistently accurately. Except for color, of course. That requires a set up or another step.
The Word HTML editor is not WYSIWYG, and shouldn't be. However, checking the results with a browser is difficult since Word locks up the text file making it unavailable to other programs, like Netscape, so long as the file is open in Word.
No software is static. The manufacturers are always issuing upgrades, as well as fixes. In the case of HTML editors, browser standards are always changing and new tags and capabilities are being added constantly. The result. Whatever HTML editor you chose to use, you will likely have to supplement it with an ASCII editor and manually tag the new stuff.
Or, buy the upgrade.