First things first. Really loved the movie, fanheart would give it a 10/10 , realistically it is probably ~ 7.5/10. So I don't wanna repeat all the things the other commenters already said about the good and the bad aspects of the film. What I'm interested in is the whole Lore aspect. More specifically how it will turn out with the sequels - which I just assume will happen because I doubt this movie will do bad at the box office.
So yeah, even though this thread is obviously spoiler marked for the movie,
if you don't know the early Warcraft games and novel lore etc and don't want to be spoiled for possible future movies, just stop reading here.
Then let's talk some lore. Overall they didn't really do any drastic change. But I think there are some of those minor changes that will impact the future story in a muuuuch bigger way than they did just in this first movie. At the end I got the impression that they are planning to kinda mix the first and second war together.
For example:
We already have the Alliance. Stormwind was never sacked, the First War isn't even over... I think? Because well there still is this huge ass Orc army that made it through the gate in time. So instead of the Humans beeing defeated and Lothar sailing north to form the Alliance of dwarves humans and high elves and start the Second War, we now already have that Alliance. During the First War.
Blackhand is dead already. Normally Orgrim kills him and takes his place, but I highly doubt that Orgrim will act as Warchief under Gul'dan after the events that happened in the movie. So they either come up with a story why he still does, or they make some other clan leader Warchief. Also during the orignal lore Orgrim taking control of the Horde was made significantly easier because Gul'dan was in a coma. But this happened because of Gul'dan was poking around in Medivh's mind looking for information during the moment Medivh died. Which leads us to
Medivh already beeing dead. Yeah well, not much to write here it's basically connected to the second part of point 2.
Durotan beeing dead. Man that REALLY caught me offguard, I didn't expect him to die this movie already. His early demise itself does not really make the story more complicated, but rather the fact that Thrall is now already set out and found by humans. So either that was a stupidly long long loooooooooong river, or Thrall was found while still in the southern kingdom. But more importantly there are no internment camps around already for him to grow up in. And that is like THE defining factor of his whole early character development, growing up in slavery.
So I went into this movie having read a lot about how there are only minor story changes. And there are, things like Orgrim beeing Frostwolf, the Garona and Lothar love arc, Dalaran already beeing in the air. But damn I went out of it thinking "Well, considering the possible sequels in the universe those are some heavy changes." And it's definitely not a bad thing per se. I think it will be really interesting to see how they proceed writing their own story while still staying true to the most important events in the orignal lore. And as long as they don't deter too far from the original stories and keep the changes minor, there will be nothing stopping me from seeing every god damn movie set in this universe!