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Personally, I pay less attention to organs in churches, so I don't know how to compare these to others I've seen.
However, from Wikipedia:

The organ has 66 voices and consists of 4,743 pipes (with a height of 11 millimeters to 10 m), including 183 Spanish trumpet resonators.
The entire 10 m high instrument weighs 36 tons.

They play one of the major roles in each church as some date for many centuries are unique in the world :)