If you're looking for some photos of the oppressive alien skitters, you may want to click right here. TV Line has a couple photos showing off the mechanized aliens along with a decent introduction to the show's plot for those that haven't been exposed to it yet.
While I don't think the show needs amazing special effects, they can't be distractingly bad. My guess is they will not be anything special but should be enough to let us immerse ourselves in the story. I just don't want awful CG from like shows Merlin and Sanctuary - at times the graphics were so bad they could ruin a serious moment with laugh out loud attempts at special effects.