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Full user review
"See where all your disk space has gone."
Shows you your volume sizes, allows you to delete offending huge files. It will even do network volumes.
Kind of slow.
There is a much faster utility called "What Size" but it they charge you a nominal fee. Considering this is free, I can wait. Must have utility! Omnigroup has an array of beautifully designed, no compromise Mac apps that you really need to take a look at.