They offer: free of charge publishing; simplified and fast publishing process; worldwide sales of work; no commitments - you and only you remain the copyright holder of your work.
Yes, several of my colleagues had Lambert publications. Our management (the scientific board) found that Lambert doesn't have the characteristics of fair and trustful publisher. I can't describe details, but there were problems with peer reviewing, time of publishing, quality of their publications etc.
Barbara, please, could you tell us on which list you mean? Is there any wider accepted list of academic publishers, I mean - not only journal publishers but those that are publishing books etc?