If there is one prophet of the Restoration who would roll around screaming in his grave at the idea that he was infallible, it is Joseph Smith. It is SO easy to forget that he is the most chastised person in the D&C - and it's not close! If he was willing to record those chastisements - and if he was willing to say what he said often about his own failings, we are judging him by a vicious standard if we turn around and expect him to be some super-genius, infallible wonderkind. I think we owe it to him to recognize his faults but honor him regardless for all the extraordinary qualities he really did have.
Along those same lines:
Brigham Young had major issues as I look at him (and I do not believe a number of things he taught, most obviously, from my multiple posts about it, that the Priesthood ban was appropriate or of God), but, seriously, who else could have held the Church together in those hellish times? When I try to look at the big picture with a charitable eye, I thank God "Brother Brigham" was around to lead the Church when he did - even with the baggage we inherited as a result. I truly believe the Church would have shattered and disappeared without him - as it was threatening to do after Joseph's death.
Life is a two-edged sword, and it's very easy to criticize even those who did remarkable things - since nearly all who do remarkable things fail mightily before, during and after the remarkable. I've been a history teacher, and that is true throughout history. Those in the lead fall often, and the ones I admire are the ones who keep getting up and living a life guaranteed to knock them down eventually every time they rise. When you fall from greater heights, it's much more visible to those around you; when you get back up and climb again to even greater heights every, single, stinking time . . . I will be the last one to condemn.
Criticism of specifics? Absolutely fine, as long as it's done charitably and with humility. Dismissal and condemnation? Absolutely not.