I have been using it for a few days. It gets better the more you use it. You can use the disply feedback box to see what the voice command engine thinks you have said. This really helps for the CALL John Doe, or DISPLAY CONTACT John Doe, commands. You can see what results are being returned. If you have a contact with the last name Courteau, it hears Court all, which it will never find in you contacts. BUT you can create nicknames for persons you call frequently (Link a firstname like Steve to the Courteau in you contacts and then you can CALL Steve, or DISPLAY CONTACT Steve. I think the biggest trick to getting this to work is to speak "normally" when you are saying your request. If you ennunciate words in your command you will mess up the results.
I like the voice command: TAKE A SCREENSHOT. It is a lot easier then pressing two buttons simultaneously for ten seconds.