SPOILERS!
How Thor should have ended.
Instead of trying to destroy the planet of the frost giants, Loki should have declared a fait accompli after killing the king of the frost giants, and ascended to the throne of the ice giant planet and remained King of Asgard. They could explain this by saying that frost giants choose kings through battle anyway, plus he's son of the previous king. He would banish Thor back to Earth without his powers, and seek to increase his empire through conquering Earth.
This would set up a reason as to why a thunder god is fighting alongside a man in a tin can, and a soldier on steroids, as well as set up a villain that poses a threat to the whole world, and would require the Avengers to stop him.
Instead we get a shitty purple cube mcguffin, and a fucking Marx Brothers impersonation from Loki (the mirror business).
PS yeah I know it's the cosmic cube, but who gives a shit, the cosmic cube was one of the stupidest concepts in the marvel universe.
