I've been somewhat reluctant to do reviews on the voice recognition software systems I've used (IBM Via Voice and Dragon NaturallySpeaking 7.0), mostly because I've used this stuff long enough that it's hard for me to give the prespective of someone trying to learn it from scratch. I admit that even with experience I still find the software available today at best inefficient compared to typing and at worst frustrating to work with. I am currently using Dragon, but not out of love. However, for those who are considering buying voice recognition software (for some of us who have a history of RSI symptoms or other handicaps that preclude typing, it can be a needed alternative), there are some pretty good reviews out there.
This review of Dragon NaturallySpeaking 8.0 is recent and fairly thorough, so I recommend giving it a read. Here's a shorter review that emphasizes DNS 8's Mobile Voice Recognition capabilities. And for Mac users, you can review the iListen review links I mentioned a few months ago.