I liked the episode, but it had one glaring problem. Everyone would've noticed sterility in a few months when the pregnancy rate dropped. Lots of specialists do nothing but work with pregnancies, and shortly after that the nurses in the maternity wards would notice that they haven't seen a baby in, oh, a few months. A more believable twist would've been that the technlogy caused second-generation sterility, so that none of the kids being born could have kids. But even that would give them a couple of decades to correct the problem through further intervensions, perhaps using Asgard cloning technology. Also missing was the fact that the Asgard would probably not let such a thing happen.
So other than it not quite making complete logical sense and not quite conforming to what's already been established (really those are minor nitpics), it was a great episode, as evidence by the fact that none of those nitpicks really mattered when you watched it.
Odd fact. When they first started with the story, they were putting the accent on the first syllable, "ashen". Someone then put the accent on the second syllable to make them sound like a race of people, and it made much more sense to everyone, hiding the true nature of the threat. "Ashen" as a regular word is how bubonic plauge victims were described, and it still triggers a reaction. I think the episode might have one instance where the first pronunciation was used.