Throughout the run of Stargate SG-1 (and in particular the first 4 seasons) there have been many interesting storylines and concepts that were never mentioned again. The Reetou are one such example that at first seems like they would've been mentioned again and could've been an interesting addition to the Stargate Universe. However, looking back it's easy to argue that because of how silly they were it was wise they were never mentioned again.
Let's face facts, it is a very silly idea: invisible crab-people terrorists. What makes the idea even worse is its execution (in terms of visual effects). The sequence where Carter moves towards and then kills a Reetou in an elevator (in particular it's arm/weapon pointing outward, and it's death) have visual effects so pathetic that it makes me cringe.
The cliché of tracking the monsters through corridors is made slightly more tolerable and forgivable by the addition of some always-great SG-1-style humour, mainly that between Jack and Daniel (especially the scene with their silent communication). Another rather funny bit is the proof of the existence of "Mother". Actually, one thing that I will always remember about this episode is the advertisement used for it when it first aired in Australia. They played this really wacky music whilst showing Reetou being blown up, and it makes me chuckle whenever I think of it. So, I guess, that's one reason why I'm being so forgiving.
But possibly the best things about this episode are Jeff Gulka's performance as Charlie (I usually judge a child actor's performance by how much they irritate me, and he didn't irritate me at all), and the relationship between Charlie and Jack. It's a very unique relationship (in terms of Stargate, sci-fi and TV in general) and it's handled quite well: not too subtle but thankfully not turned into melodrama. Unfortunately, we never find out what happens to Charlie, which is a great disappointment.
So, despite some big flaws with the episode, it's not completely ruined. It remains an average episode in terms of Stargate, which isn't a bad thing at all. In terms of showing it to a soon-to-be SG-1 fan...this is once again another episode that isn't one they should avoid but also isn't a must-see either. It doesn't add anything more to the story arc or Universe (except for a minor point in "Fair Game"), but also isn’t an episode so bad it will turn them off the show altogether. Once again, I'll leave the choice up to you.