Saw this today (thank you, T-Mobile) was a lot better than I expected. I know almost nothing about WoW, but went with a friend who is HUGE into it. Talked about everything over a burger after.
The biggest failing of the movie is that, with such a wealth of established lore, there was almost no world building. It was constantly "here's this, and we're going to use it in this scene and move on".
The honor of the Orcs should have been firmly established in the first 10 minutes of the movie. The sanctity of the one-on-one fights should have been established then as well, so that when Guldan cheats, the audience understands (instead of having to have the crowd yell 'he cheated!').
The scene of Callan returning to the sky wizards had zero emotion, because we had nothing to connect it to. Sure, he tells us that they were upset when he walked away, but that's it. His departure from them should have been shown early in the film as well. Also, the humans seemed to hate the sky wizards for some reason (they saw the tattoo on Callan and he instantly had to tell him that he wasn't one of them anymore) but then nothing came of that.
I think, for those into WoW, scenes carried a lot more weight, but for those of us who know zip, they didn't lay the groundwork.
Finally, I had a hard time getting over the modern/clean look of some of the cast, specifically Callan and Medivh. It was just a step or two away from cosplayers, rather than characters that belonged in the world.
The orcs were great, Durotan and Ogrim were great, as was Blackhand and Guldan.
Oh, Anduin's son (another who looked like he wandered in from another movie) should have been cut entirely. Remove that relationship, give the film time to a bit more worldbuilding and strengthen the relationship between Anduin and the king, and you'd have a tighter, better film, IMO.
edit: actually, speaking of worldbuilding, there really needed to be a lot more. They were in a tavern, but the tavern was completely dead, no barkeep, no customers, etc. We saw the villages being plundered, but we should have seen them (even for a moment) in peace. Again, the orc code of honor should have had a scene or two defining it. It's clearly a world with a lot of history, a lot of established backstory, but none of it was up on the screen.