Not having watched any trailers I was unspoiled for Carson reappearing at the end, so that really took me by surprise. I mean, how did that happen? Did Michael clone him? I guess we'll find out eventually, for now I'm all: flail! Carson!
Otherwise, I'm not sure handing over their research to Todd won't come back to bite them later, even though they hope the Wraith will just kill each other with it, because their dubious science projects always seem to do. (see Michael, I mean, do they really want more mad scientist Wraith projects?) They tread kind of in the Ancients' footsteps that way, their science experiments are still killing people thousands of years later. Also, right now 30% of the people Michael infects die, but at least 70% can't be eaten afterwards, whereas by helping Todd to make his Wraith immune to the disease, still a third die, and but the rest will work as food again. That's not really helping the humans. Unless I missed something.
Still I liked that Michael reappeared, it worked for me how creepily obsessed with Teyla he is. I hope that storyline will come to good resolution, preferably one in which not all Athosians end up dead... Though I wondered what exactly he's been doing to the Athosians. Brainwashed them in addition to making them hybrid super-soldiers?