Turns out I was wrong to trust the reviews
The Warcraft movie is good. Not phenomenal, but good. A very solid fantasy movie, especially compared to other fantasy movies, of which 90% are crap. Especially considering how bad it could have been!
Most interestingly, my wife liked it too. And she has never play Warcraft anything. So did a friend of hers.
Is the movie perfect? No. It has flaws, like those that many reviewers called out. But those flaws don't really weigh all that heavy. I honestly wish that they made a second (and third ..) movie. The Warcraft story until the end of WotLK is pretty good - and even more so if the movie takes the chance to improve a bit on it.
Finally, the story of Arthas is not easy to tell well. But if it is, it has a huge potential!
And, finally, watching that movie made me wish Blizzard made a solo RPG in the World of Warcraft. There's some potential there, too. It's a pity to leave all the AAA solo open-world RPGs to Bethesda.