"Bound" essentially feels like "Rajin" done right. Season 3's attempt to have an alien lady attempt to seduce crewmembers, with an ulterior motive tried too hard to be edgy and looked like a juvenile attempt at titillation to boost the ratings. At least "Bound" had that women control the men to redeem it slightly.
In the same way "Observer Effect" retreads "The Crossing", but does non-corporeal posession with intelligence... going for the experiments on a lower species angle. Instead of an excuse to have Reed behave like a horny teenager around T'Pol... cutting between one character acting possessed and then switching to another, became something more creepy.