In ongoing serial fiction, characters get killed off (And replaced.) and resurrected all the time. Heck, do you think that there wasn't a backlash when Gwen Stacy died? Cap being a nazi, that wasn't the real Cap, was It? Superheroes go evil all the time, and later on that almost always gets retconned. Remember Hal Jordan? Or The Crossing? Etc. In these cases, ruined means don't like the stories or directions.
It's definitely ruined. I'm done with Marvel after 20 years and so are many others.
Thanos is the only title I collect now.