I love every episode where the Asgard are involved ... especially Thor. This is their first real episode ... and it's great!
Thor comes to save the day and whip the goa'ulds a*s, after SG-1 destroyed the only line of defense the planet had against the goa'uld.
If I were the Cimmerians, I would've been a little peeved off at SG-1 for doing so ... but they were so friendly and willing to help, that it almost made it unrealistic :)
Except for that, the episode was awesome: we find out about the true appearance of the Asgard (the best ally earth will have against the goa'uld) and we also find out that they are much more technologically advanced than the goa'uld ... and they are good!
This episode helps with the continuity of the show (it's a sequel to the "Thor's hammer" episode in season 1 ) and sets up a lot more episodes where the friendship and alliance between the asgard and earth is renewed. And a series which keeps the continuity going in the story line, deserves great praise. Great stuff!