I have an issue here, I don't own Thor 2. And searching for it on Sky or TV, wasn't to be.
This is the first one I'm going on memory. I last saw it like 8 months ago and I'd say it was mediocre but not because of Thor and Loki or the villain. It was the Natalie Portman stuff, the 'romance' of the girl character and the whole science thing.
Lack of Balder and Enchantress... still.
This is the first true film as well where the bogging down too and first where it was highlighted that the Infinity Gems are not gems. What confused me too is that according to MCUs own Asgard is in space yet these 'realms' could could link. It was kinda confusing.
However, all this is made up for by great interaction between Thor and Loki and their love for Frigga, that side of things and Loki's trickery is really well done and shows how good of a character he is.