Like negativity around any demographic it could be construed as a prejudicial, although it depends on the context. There are behaviours of course, particularly of late that put men in a very bad light sexual abuse, grooming, mass rape in war torn countries, as a woman one can't help being horrified by some of the awful things that befall women, but that is not men per se, just a minority. . In many parts of the world life hasn't improved for women who live under the strictures of a patriarchal society. In worst case scenarios such as Afghanistan women and girls have the most awful lives controlled by absolutely the vilest of men.
Having said all that I don't like to hear women slag off men as if they are all some sub species it isn't fair, I think we all know how our hackles rise when it's done the other way, even if we, as women, have had to put up with that, probably since the beginning of time.