Stargate SG-1 delivers one of the best cliffhanger endings I have ever seen. The episode as a whole is fantastic and stands up to numerous repeat viewings. It starts with a typical visit to a planet that hasn't progressed as far as ours, Camelot, the scenes here are well written and hugely enjoyable. Mitchell's fight with the knight is pretty damn good, and you genuinally worry for his safety. Mitchell's status as action man is secured too and you realise just how much better the show has got since he joined. Daniel has a rare "screw it" moment by shooting the crystals and Michael Shanks' performance is as good as it's ever been. the comedy moments are top notch too, the unexpected beamings of Mitchell and Jackson and there responses to it are highly amusing.
The end battle is the best scene the ever has ever had. My jaw was on the floor throughout. Everything about it was done fantastically and by the end of it, it genuinally appears that everyone has been killed except Carter, and her survival doesn't appear likely.
And Vala's appearence in the final seconds only make the episode that much better, the score over the final minute is equally impressive.
Things that aren't so good? Can't think of anything substantial, I would have liked Teal'c to be in the episode a little more and it wouldn't have hurt to have Landry involved in some way but these are minor. The episode is the best the show has seen and everything a season finale should be.
Bring on Season 10