I thought the ending was perfect, even though it felt very uncomfortable to kill these innocent doctors who were just trying to save themselves and the whole world. Which is good, because Joel probably felt uncomfortable himself. Having to live with such a giant burden for selfish reasons.
It opened up an interesting situation in the very end. You couldn't really be sure if Ellie would've wanted to be killed for the good of humanity. Joel wouldn't even give her that option so even though they both knew that they probably did the wrong thing they went with it.
Either way the ending opens up a giant potential for interesting stories in the sequel and I can't wait for that to see.
If you demand respect or gratitude for your volunteer work, you're doing volunteering wrong.
