The biggest problem for Thor: The Dark World was how badly a great decision played out. The hiring of Game Of Thrones director Alan Taylor should have been perfect to replace Kenneth Branagh; he should have brought the right blend of theatricality and fantasy with that typical Westeros eye for drama.
Sadly, his film was a boring misfire that took its good ideas - like pretty much everything it does with Loki - and buried them in drabness. There are other good flash-points - but there's too much focus on villains who simply aren't interesting enough to warrant it. Again, they have their moments - like the idea of a select few "evolving" into The Kursed - but in Taylor's hands they become no more than Doctor Who monster of the week types.
It also doesn't help that there is an awful, distracting attempt to alleviate the tension by having too many comic relief characters - like Kat Dennings' Darcy and Stellan Skarsgard's utterly disrespected Selvig who are very close to unwatchable.