The voice command has been very hit or miss for me on my iphone 5. I suspect it may have something to do with the bluetooth connection to my dodge dart, because I also have issues with siri while the phone is connected to the car via bluetooth. Waze's voice control was working rather well for awhile but now I haven't been able to get it to work at all.

To use siri at all while connected I have to make it open (where it makes the prompt sound but immediately stops listening) and then quickly hold the button again to get a second prompt which will let me say something to do.

When I use the 3 finger tap on Waze it pops up and says listening and even seems to register the command (immediately shows the "working" symbol when I stop talking) but then says it didn't understand (even something simple as "report hazard" which has worked in the past). It then pops up as listening again, but immediately cancels itself and returns to map view. This is similar to what siri does when initially called.