Speaking only for myself here, but the only reason I have for running LibreOffice at all is to import MSOffice files sent to me by colleagues or by branches of the US government. So intercompatibility with MSOffice is for me the most important part of the review. And I can confirm that LO 4.0 is no better than LO 3.6 at importing MS Office files. So the commenters are making a valid complaint.
It is not a matter of whose "fault" it is, it's a question of whether or not LO 4.0 solves (or at least ameliorates) a long-standing problem. Unfortunately, it doesn't. So I will continue to use MS Office running under Wine until a workable alternative comes along.