I know that this type of story has been told a great deal over the years, including SG-1, but I have to say that they did a damn fine job of telling it this time. Only slightly spoiled before watching it I was still anxious to see what would happen next, how they revealed the truth. Dropping little clues here and there. I've seen it better, but that's not to say that I wasn't enjoying myself.
Once the two teams met, I was grinning the entire time. From Sheppard's reaction to the two McKays to Ronan and Teyla (the copies) discussing how they'd react. Actually just the general back and forth between each set of characters talking. Sheppard and Weir's conversation was very well done. And I just felt bad for everyone involved. I know that folks don't like how they revealed that the real Elizabeth was dead, but I liked how they did it and how Sheppard was sort of in denial by saying that they wouldn't treat her any differently if she came back with them.
I hoped or expected a bit more of an ending for the copies, but I liked Sheppard's facing the Replicators and that smirk on his face.
The little scenes with Rodney and Zelenka and then Rodney and Sheppard at the end. The one with Zelenka was touching and Rodney surprised me a bit. Nice!
When they showed the ships appearing on the screen a bit at a time was cool, and I really liked how it went dark and we just heard more ships appearing and then Rodney's 'Oh crap..."