Throughout the first 2 seasons of SG1 there were some very disappointing episodes. However, amongst there were the true classics, the brilliant episodes that changed the series and showed its true potential. As you've probably guessed from my score, I consider this to be one of those episodes.
Practically everything about this episode is brilliant. For one thing you have the humour comes standard in every episode of SG1, but along with it you have some great serious dialogue that I found myself quoting along with when I recently watched this episode again.
What else make this a great episode are its strong human and emotional elements. This is perhaps most obvious in the scenes involving Jacob talking with a dying Selmac. Every moment seems to have been handled perfectly. Two key bits that I love are "I have decided I like you", and "Goodbye, dear friend". That last one is quite powerful emotionally, and I think rivals the best SG1 has offered over the years.
So, in summary I'd say this is one of the greatest episodes from the first 2, no 3 seasons of SG1. Obviously this is a must-see episode for any soon-to-be SG1 fan, and I'm sure they'll love it too.