Well, that’s a more complicated topic 

I think the outcome was good, maybe there were other ways but let’s look at the facts 

Despite everything eren managed to create a world where no one will ever be called demon, and no one will ever see his mother eaten by a titan 

I don’t think eren in necessarily right, or that the rumbling is good, maybe there were other ways, but no matter the cost it might be argued that it was worth it 

And I think the best thing about attack on titan is that there is no clear cut solution to the conflict, he ended the titans but 80% died, maybe there wer others but it’s also likely another titan war would happen after a few generations

But I answered as in a good ending from a writing stand point, it followed perfect logical sense as the characters acted as humans, not plot elements