Well the movie is based on the Warcraft 1, with some changes, and some additions from the current WoW. They said it the best on Blizzcon, the movie is for all Warcraft fans, but they also had to somehow find a way to introduce the movie to normal audiences who never heard of Warcraft.
As for the CGI, ppl need to chill about it, the movies comes out in like 7 months, CGI can be polished fine by then, just remember the Jurassic World trailer and how everyone was ****ting on it because of bad CGI dinosaurs, but in the movie it all looked fine.
But I got to say the part with lil' Thrall being sent down the river like Moses was funny tho, no need for that, but w/e.