Typing for me has always been a struggle; too many errors to correct. I'm basically a two-figured typist.
Dragon really makes me more efficient. I use it to dicate file memos after I meet with a client, emails, letters, "todo" items into a database, and time slips, all into different software progams. I find that I'm more willing to be prompt in my responses to email, because the effort is less. My time records are more accurate and descriptive, because my typing speed is not now a limiting factor. My file memos are now more descriptive as well, because the effort is so dramatically reduced.
There certainly are errors created by Dragon; for me they are simply fewer and easier to correct. And the errors are fewer, as I learn how to speak, and it learns my common words and pronunciations. I suppose every user will encounter a different benefit equation (typing skill vs perhaps, voice quality), but it surely has made me a better, more efficient attorney.
Dragon is a major advance for me.