Any episode involving Ronon fighting the Wraith seems to showcase Atlantis at its best. A heart pumping, cutting edge adventure with plenty of drama and action, last year it was Sateda, this year it's Reunion. Compared to the mediocre Doppelganger (which I saw before this) Reunion is in a different league. The new tone of the series is evident here, with the violence having been toned up considerably (the throat slashing scene a particular example).
All characters and actors are on top form again and the writers manage to introduce Carter as the new leader of Atlantis quite well, which is something coming from me as I am against having her on the show.
The episode's primary detractor is its slow start, it messes around with Carter's introduction and Ronon's "I wanna bring my friend's to Atlantis" angst before getting to the good stuff, still, a minor niggle.
So, while not quite as action packed as Sateda, this episode is still just as enjoyable and is less Ronon-centric, getting the rest of the crew involved in the action as well, a gripping, exciting and fun episode, may this be an indication of things to come.