Evolutionarily, this does not seem terribly plausible. Even parasitic organisms have to have a plausible niche within an ecosystem, else become extinct. How would this race have evolved to feed on humans specifically? No food source prior to humans has yet been referenced; feeding on humans has been specifically stated on the web site and demonstrated in the initial episode. How did the Wraith come into being? I'm sure that question will eventually be answered, and it definitely needs to be. Their demeanor and mien also reminded me slightly of Klingons.
Additionally, every advanced human culture that we know of has thinkers and philosophers. Granted, the Wraith are alien, but . . . does it make logical sense to talk with your food? If they're that advanced, would they not have some recognition of consciousness? Talking creates a connection and a certain intimacy. Not necessarily respect, mind you: we've had wars and plenty of human enslavement despite being able to talk with one another . . . but while we do kill one another for various reasons, cannibalism is fairly rare in most advanced cultures.
The makeup looks really good, and they did a decent job with the special effects, I'm just not sold on the villains so far.
I also found Teyla Emmagan annoying. Some actors can carry off stilted speech that is supposed to represent a not-quite-as-advanced human culture, but Rachel Luttrell isn't managing it very well thus far, in my opinion. Joe Flanigan (Major John Sheppard) sounds like Owen Wilson to me.
We'll see where it goes. I will say that I think the SciFi Channel is being very smart in putting the parent show in the time slot just before the spin-off for a full season, to allow time for the viewership to get comfortable with the new cast and make it a habit to tune in.