Having a high user rating and a low critic rating probably means it's pretty all right if you don't think about it much/at all. Well, that and initial release score inflation. Average IMDb voter goes to cinema, hears loud noises and some approximation of an image, permanently lowers their hair cell count, has an okay time, 10/10, didn't have noteworthy issues they can think of. They tend not to be terribly disagreeable at release unless something is irrevocably and unforgivably shithouse on an incredibly obvious level.
In addition to this there are probably quite a few people (given Blizzard's somewhat noteworthy fanbase) who are voting 10/10 on sheer principle (the principle being that they're mostly twats) and aren't balanced out by people who are voting 1/10 on sheer principle (because the opposing side hasn't had time to form or doesn't give a shit... yet, though there may be a user review backlash in the future).
Overall, user reviews are a load of shit when fanboys or hateboners get involved, since either of those try to game the score system for dumbfuck reasons that defeat the whole point of having user reviews to begin with. They're not terribly useful for anything aside from already established works at least a couple of years after release. Critical reviews are probably more trustworthy if you have much in the way of doubts to begin with and intend to watch the film with a critical rather than 'let's watch whatever' mindset.
To somewhat qualify all this, my brother saw Warcraft and compared it favorably to watching 4-hour cuts of the first two LOTR films back-to-back, an experience that very solidly persuaded him to give the last one a pass with little to no reservations.