Okay Sara dictation is nothing like siri nore siri dictation but it does work really well ( i havent tested on ios 6) basically what it does is it listens to what you say once your finish speaking it automatically copy's your voice into text in the clipboard you would have to then paste it onto a notepad, an email or where you'd like, Facebook post ect.
Now if your on 6.0.1 or even 6.1 you can easily port Siri which will then give you the ability to use siri on that phone. Best of all it works as I'm using it ,You will need to be Jailbroken and you will need to add a repository into Cydia.
Repo: http:/Bassankassem.myrepospace.com/
Once you add the above Repo do a search for [Ac!d]-siri iOS-6.1.0 install it
After installing Reboot your IPhone ( be sure to enable siri within settings after reboot also)
Note if your on a Terhered Jailbreak you will need a PC to boot the iPhone.