I have played with the talking and brraille cumpasses.  I preffer the 
talking one for a number of reasons.
1.  You can operate it one handed.  Therefore you can be moving while 
checking your direction, and you don't have to find a way to keep your cane 
from falling over; or your dog from wandering away.
2.  Motion doesn't effect your reading.  The needle on the face is fragile, 
so you have to stop just to read it.
This is one of the few places where speech is better than braille.