That was my take on the tumor as well. That and having her die before Peter was kidnapped would be something of a mercy in his mind versus her thinking/knowing space guys took her son, and Ego was likely involved. I feel like that's why the Ravagers come get Peter immediately after she dies. Ego talks about the insignificance of life compared to his immortality, so not surprising that he would just end her if he's not coming back.
We saw it Friday on the IMAX 3-D screen and it was pretty awesome. I did feel a spark of let down versus the first one, but I think it's hard to capture that magic in a bottle twice. I read a review this weekend with similar thoughts - it's funnier than most movies and better written than most movies and more entertaining than most movies, but it isn't the original. I think the group is also at their best when they all play off each other and having them spread out for most of the movie hurt that dynamic. That said, it was still the best movie I've seen this year by far. I think I laughed a lot more through this one too. I'm glad I didn't read anything about the movie in advance - seeing Sly and later the original Guardians was a nice surprise.
Without throwing out spoilers, I loved references to Hasslehoff and Mary Poppins, Baby Groot and his inability to follow directions (nice play on how we can't understand him), Howard the Duck and Stan Lee cameos, Pretty much anything Drax says ("you're disgusting"), Kurt Russell (who does not look 66), Trash Panda, and Rocket's all too obvious winking. Mantis was a nice addition to the cast as well.
The end credits were fun too. The extra scenes were great, but they had some other little bits of animation through all of it as well. If you watch closely, some of the lines throughout the credits just say "I AM GROOT" then change to the actual name after a few seconds. Did anyone spot Goldblum's Grandmaster in one of the picture bubbles? Not even in the Guardians movie, but a nice link to Thor's upcoming flick.
