Everything in this episode was good: The Wraith and Atlantis crew fighting together to finally rid the Pegasus Galaxy of the Replicators; Rodney's plan to cause the nanites to join a supermass, Teyla *finally* revealing she is pregnant, and the resulting character development between Teyla and Sheppard, and Teyla and Ronon, and the special effects were top-notch. The best part of the episode goes to the scene where the Atlantis crew, the Wraith and Larrin's fleet were attacking the Replicators in orbit of their planet. One of the best battles seen, and one of the best special effects ever.
But what made this episode gold was that last 30 seconds or so, where it was revealed that not only a Replicator ship survived, but Weir did too! I just hope she remains evil, because that would be so totally awesome!