I'm not a follower of comics so I have no expectations going in. If they do something not in keeping with the character or storyline as known elsewhere I wouldn't know. Works to my advantage.
What I like most about these movies is the bigness. The venue is big - multiple worlds. The characters are big - many are gods. The stories can be complex - motives within motives, illusion within illusion.
Then there is Natalie Portman, an excellent actor I have watched grow up. Anthony Hopkins is legend. Chris Hemsworth - best Thor ever.
Overall, it is just what I like - excellent production values, excellent sound track, excellent actors, an interesting plot, engaging visuals, entertaining subplots, action, adventure. And, the deliciousness of Loki.