How consistent/reliable is the lore?

A question about the lore. I've been wanting to get a little more into the story. Read the books. Not immediately dump the memory of every quest as soon as I click complete.

Question is - how consistent is the lore in the Warcraft universe? In your opinion, do they know what they're doing? Or do they just kinda make each every and character up as it goes along? Do you get the sense that characters actually have motivations and that stories follow logically? Or is it more like "well, let's have Medivh do a thing here, and then uh let's have Illidan do something for some reason..."

Compare it if you like to something like Harry Potter, A Song of Ice and Fire, or Wheel of Time - any other series which spanned a number of years and sprawled in scope. Do you think Warcraft is more, less, or as focused/unfocused as those stories?