First off, my one star review is not for the content here. This is Joan Baez' first three albums, the first a shared artist effort originally on Veritas, and the latter two originally on Vanguard(who still own the master tapes). The two Vanguard albums, particularly the first, are the bedrock upon which she earned her reputation, and they are very fine examples of the folk movement. They belong in the collection of anyone interested in Baez or that movement.
That said, this collection is a quite nasty attempt to use a loophole in copyright law (soon to be closed) to reissue music without paying master royalties. Not a penny from this release goes to Baez (who is still alive, and who is not rich), nor the label that paid to create and release this music. The albums themselves are rather mediocre sounding, and that's to be expected since the label has no access to the masters and the best they can do is take something already released and fiddle with it (usually to the detriment of the music). The liner notes are poor, and the cover picture...well, you can take a look for yourself and decide if that's really the most flattering cover you could imagine.
Every one of these copyright loophole releases robs musicians (or their estates) of their livelihood, and decreases the chances that the labels who actually own the masters will ever go back and create a better product.
Ultimately, there is absolutely no difference between buying this set and obtaining this music through any nefarious download site, except for the fact that by buying this set, you have the privilege to pay a leach of a middleman.