"Weird" is such a relative term that I am not sure how it has any meaning. Lots of things that make a lot of sense seem weird to those who don't understand the principles behind them - look at science, for example. So just because a way of doing something seems unusual doesn't bother me at all; if much of what he did was being done for the first or the only time, it can be expected to be done differently.
As far as charges of mental illness, I don't think there is any evidence for it unless we assume that everyone who claims to talk to God is mentally ill. Which plenty of people do. As far as the papermill, it was actually a printing press; the legality of his actions as mayor of the city of Nauvoo (by which authority he declared a newspaper printing articles hostile to him was a "public nuisance") are, I think, still debated, but since it ended up leading to his death anyways, it's not like he got away with anything.