I found the art easy to work with. The time savings you gain by using this depends upon your need for covers but I found this product useful and worth the money. Even if you modify the heck out of the art for final production, it provides an easy "plug and play" method of generating quality covers quickly. - I have 6 of these collections and have various covers from each used in up-coming product offerings. The only down-side is your products look very similar to other publishers works (since many people are using these) and you need to Mod like crazy to create a clearly differentiable "branding" of your work... because many people judge an e-book by it's cover.
I bought this product as part of a bundle. This is the point in the series where these become useful to me as a publisher who's decent with graphic arts. I can use these covers, at the very least, for insiration and will probably end up using them "as is" for a series or two down the road.