In order for compost to develop rapidly, it has to be mixed, turned. This compost bin doesn't appear to make that any easier than a simple piece of wire mesh to hold the compost in a pile, or a simple scrap lumber device nailed together, about the same size.
This soilsaver device is about 2 1/3 feet by 2 1/3 feet by 2 2/3 feet high. That's about 15 cubic feet. Which means after you fill it up once, you will end up with compost measuring about 3/4 of 1 cubic foot. A small bucketful. About 1 foot by 1 foot by about 3/4 feet high. Probably less. If you spread this amt of compost 2 inches thick, it will cover an area about 2 feet 2 inches by 2 feet 2 inches , about 4.5 square feet. Probably less.
A bin this size is probably plenty big enough to compost kitchen waste, for 4 people, but not big enouhg to feed a garden area any more than about 2 feet by 2 feet. You just need more compost for even the smallest garden, if you want to reduce significantly reduce dependency or industrially produced fertilizer.
People don't seem to realize the "huge" amount of space needed to produce a practical amount of compost.
For my 2000 sq foot garden, I had about 720 cubic feet of leaves, grass clippings, kitchen waste, seaweed, mowed and pulled green manures and plant parts not eaten (such as corn stalks, clover, rye grass, oat straw, soybean straw, etcetera, mostly leaves and lawn-grass clippings -- my lawn grass was mostly rye), in 3 piles, at different stages of decomposition. Each pile 4 feet wide by 3 feet high by 20 feet long. And this was not quite enough compost.