Honestly the only issue I truly have an actual problem with, is pretty much covered by most here already- it was rushed.
I could go on a year long rant about Medivh and Garona (BTW during the first war, Gul'dan was the only one who knew her mothers heritage- everyone else, including Garona, thought she was half human and accepted it as fact- so first war movie saying shes half human is actually fine- but then the medivh stuff and.....*ahem*)
I can scream and rant about Llane not being assassinated in stormwind, or about Stormwind never actually getting sacked, or of the formation of the Alliance of...well I guess not Lorderon now....
I can rant about Doomhammer being frostwolf. About Blackhand being an idiot. There are so...so many more nitpicky things that I can complain about as someone who has followed the lore since inception.
But in the context of a movie? The majority of those really aren't mandatory; and could be changed for a movie audience. (Bright side of Garona being Medivhs daughter is no Med'an, so hey there's that eh?)
But what killed it for me, and imo for new audiences as well, was the lack of character development. They tried to shove way too much story into one movie. Personally I feel like Gul'dan should have been kept in the shadows, as he was in the first war, and let Blackhand and the blackrocks play the antogonist, have Gul'dan there for sure, acknowledge what he did and his manipulation of Blackhand, but there was no need to even have baby Thrall or Durotan there at all for this movie, focus on Doomhammer, Blackhand, and Garona with minor Gul'dan for the horde, and on Lothar, Medivh, Llane, and maybe Khadgar for the Alliance.
Before I go into another rant- my point is that they tried to shove characters that had roles in the first war, but whose roles were either completely unknown or well hidden during the actual events of said war, and brought to light later. This also needed to be a 3 hour movie.
tl;dr - Sure I liked it and hope they make another, with less rushed character development. But if I am being totally honest; I think it would have been better done as an HBO series, or on another network a la Black Sails or Vikings. (fun fact- actor playing Lothar is actually in Vikings)