If you mean by postmodernism that thinking and questioning things is good, then there could be nothing wrong with it.
But if you mean that postmodernism means tolerance to all types of views and beliefs, then I see a couple dangers in it, but I'll just name the one.
Postmodernism in this way can create an idealistic method of tolerance to those who are tolerant or "postmodern", but then the postmodernist automatically becomes intolerant of those who are intolerant.
I've seen too many people become intolerant for the sake of tolerance. Crazy huh?