I'm not sure wheather or not the wirters at the start of season 5 knew there wasn't going to be a season 6, but in my opinion this is the turning point of the show. It is a real drive for the plot of the upcoming movie and from what happens in this episode and next, it should be a doozy.
Dr. Jackson and McKay find a secret lab and soon after encounter a race of robototic sentiants. There is plenty of action to be had here as the b plot is just as good with Todd the wraith meeting on the Deaudlus to perfect the virus causing wraith to become human.
I'm only writing this review as I've seen a preview on youtube for the 'The Lost Tribe' and let me tell you it is a guarntee series classic moment that will take your breath away and you saying F&^K ME.
PS: I shouldn't have watched it as I ruined the episode for myself. You have been warned.