This is certainly a great idea: all 7 of JC's Sun albums, in reissued form with extra tracks, all bundled up and sold at a slight discount over regular price for each. The only gotcha is that you'll have plenty of multiple song versions and duplication. Time/Life (yes, THAT Time/Life) just recently came out with an expert set that just includes 1 version of every Sun song he ever did (61 total), and it's usually the un-embellished version, for about half the price of this 7-disc monster. And there's always the exhaustive old Bear Family set. So you've got options, just pick the one that's best for you.
This album is a priceless collection of "The Man in Black." His unique style and voice can never be replaced.