The purpose is to pass traffic information to those that need it. It is supposed to reduce radio traffic and improve safety. There are at least two voices but they both have a similar grumpy what-idiot-move-will-I-see-next tone. It works well with moderate traffic levels, but I think it breaks down at high traffic levels. Personally I'd like to see a tower there, OR a full length taxiway big enough for a B737. I once had to wait on the ground for 40 minutes because there was a string of arrivals all 1 minute apart. The taxiway would greatly improve the flow.