Base Breaker: The ending of Gillen's run is shaping up to be this. The majority of fans seem to feel it was incredible, heartbreaking but necessary, and a really well-executed criticism on the way mainstream superhero comics are written. There is, however, a small but rather vocal minority of fans that think it was a slap in the face to other Marvel writers and completely reverses the supposed message of the story in the interest of furthering a pretentious artistic vision.
Family-Unfriendly Aesop: Kieron Gillenclaims otherwise, but the message of the ending basically boils down to this: you can do your best, try your hardest, and basically do everything you can in order to change yourself and defy people's expectations, but in the end you will always be what you always were and what everyone expected you to be. Because even if kid Loki succeeded in being a hero and not being evil in the end, he was only one part of Loki and, as kid Loki said, Loki overall ultimately demonstrated that he was incapable of changing due to the very nature of his plan to change
Fridge Brilliance: If you re-read Loki's story, you'd notice that Ikol only appears and talks to Loki when Loki is either alone or in the company of people/beings that either already know Ikol's true nature, or they wouldn't care. This is really subtle foreshadowing of the fact that Ikol doesn't exist outside of Loki's head.
Too Good to Last: The Lady Sif run; a comic with a female lead character (one who has had precious little to do in her history), great art, and better writing than some of the other Marvel books at the time? No way it could last...