For its age, the machine was nothing short of stunning. Its accuracy, although not perfect, was good enough to point you in the right direction as to where in the sky to look for all the major heavenly bodies visible to the naked eye, and was clever enough to correctly predict eclipses of both the sun and the moon, as well as almost certainly showing the apparent backwards and forwards movement of the planets (retrograde motion) as they track across the night sky over a period of months or years.
This meant the operator could wind the mechanism forwards to any given date - months or even years into the future - and know for certain what phase the moon would be in, where the planets would be in the sky and, and if there was an eclipse likely to be seen.
These were all massively useful bits of information if you used the the night sky to gauge the passage of time for the purposes of debt collection, crop planting or harvesting, setting religious festivals, or just simply teaching others how the universe appeared to work. Their understanding of the mechanics of our solar system were fundamentally wrong in that they assumed that the Earth was at the center rather than the sun, but the machine still worked as it relied entirely on observed data - they simply misinterpreted what they were seeing.
I've been working on my own replica of the mechanism for the past few years - seemed a good idea at the time - with a view to maybe selling the odd one or two, so thank you Google for throwing it into the lime light again!