The story makes zero sense.
A major plot point of the story is Tyreal turning into a human, and this has got to be the biggest plot hole in the history of storytelling. Humans are angel/demon hybrids, so it makes zero sense that Tyrael can suddenly, of his own choosing become a human. Previous fallen angels, like Izual didn't become a human. So how is it possible for Tyrael to magically turn into an angel/demon hybrid?
The ending was cheesy and and felt like it was ripped straight off a Disney movie. So Tyrael can now just suddenly become the archangel of wisdom. It doesn't even make sense why he would stop being the archangel of justice, and it cheapens the power of the Angiris Council that any angel can become a different aspect as if flipping a switch. So all the answers to the cosmos just got downloaded onto Tyrael's brain?
The whole deus ex machina ending of you're so screwed, Diablo is going to corrupt the Crystal Arch, only to at the last minute, obviously be defeated by the characters, is also pretty lame storytelling. Although this last point is true of all Diablo games.
Look at the Diablo 2 ending. That was one of the most well written, WTF, OMG ending I've ever seen. This Disney ending is a disgrace in comparison. With that said, Diablo 3's story was bad, but no where near as bad as SC2. That game's story is a sad and cheesy joke and destroyed all character development from the previous game. At least Tyrael is a badass and he's characterization was well done and the Sacrifice cinematic was awesome (dispite it making no sense that he is now human). Being better than SC2 isn't any feat, even a 10 year old can write a more logical, consistent and compelling story than SC2.
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