Everyone is complaining about those final fights, but to be honest, I thought they were perfect. You get a long, epic battle with the frost giants that alone is more action than IM 2 had. By the time Thor meets up with Loki to fight, all you care about by that stage is the characters. You want a confrontation, but the words and drama of it all is so great, better than a fight would be anyway. The way they're developed, it wouldn't even make sense for them to have an EPIC battle. Loki is fighting out of desperation and Thor doesn't even want to fight him. It's the breaking point of brewing tension that in the narrative, serves to show Loki finally giving up his plans and lashing out. We needed that, without him COMPLETELY going evil, to develop him and give him motivation for an evil and twisted plot as the villain in Avengers.