I enjoyed this episode. For some reason, it felt short to me, probably because of the time it took for the first part of the story to happen - to realize what was going on. It was an homage to Double Jeopardy, and I liked the two McKays together! But in Double Jeopardy, they didn't have to spend so much time with the introduction because a previous episode already established the existence of the robots.
I was going to nag a lot about Carter not being on the base and not being mentioned once. However, once they explained what was going on, it made sense because Weir never knew Carter took over Atlantis. BUT, later on when we get back to the real Atlantis, there was again no mention of Carter, who really should have at least been notified and should be giving the go-ahead for Sheppard to meet with the duplicates. Anyway, no big nagging this time.
Now that Carter's vision in The Seer has been realized, we can stop guessing! And they have a machine that can track the replicator ships, which is helpful.
The big news of the episode, though, is the fate of Dr. Weir - or is it? In sci-fi, no one dies! Regardless, it was nice to see Torri as Weir again.