Mine is going great. Sometimes with the not so easy to say band names like "Tarja Truennuen" or "Lordi" it get's tripped up, but nothing major. I actually have learned to talk like it does, so it can understand me better, lol.
I get on the fordsyncforum.com and syncmyride.com for more info all the time to learn about advanced features. Some menus are only available through voice commands, such as the "Advanced Voice COmmands" and where you can have her shut up after every button press.
It's amazing. I have no problems with mine. ALthough I with it would stay on my USB. Everytime I start the vehicle I have to tell it to go to USB again. That's annoying.
For those of you whom like Aftermarket sound equipment like high end amps, subwoofers (SQ & SPL) as well as aftermarket head units, Metra is coming out with an interface kit that allows Sync operation through other HUs. This allows you to customize your ride and retain SYnc.