Except that it silently adds the BOM, which breaks a lot of things.
Well, yes ... but others like Notepad++ even break my umlauts in the first place ;-)
So for real Unicode work use a special Unicode text editor like SC UniPad (http://www.unipad.org). BTW I have written some more on the hassles of UTF-8 and BOM at http://docs.moodle.org/en/UTF-8_and_BOM
Frank