I have one- its great. We have the round black one, it has 3 layers with holes and one bottom layer that catches the juice. You start out with one layer and work your way up to three, and then empty out the bottom layer onto your garden and put it on top etc.... The juice is fabulous, I water it down about 10-1 ratio and put on my veges once a week.
The rules are no meat, dairy, citrus, bread, onion/garlic. They also dont like too much of one item, and will not touch celery leaves (smart worms!) The best thing is to chop items up smaller, so not whole fruit. Put a sheet of wet newspaper over the top of them at all times, and keep moist. Put them in the shade, with not to much rain. we had ours on the west coast in the garage due to the rain.
I would recommend one, they go hand and hand with a compost as they only need food a couple of times a week, the rest can go in the compost. gosh, a novel, anymore questions ask away.