My favorite scene in the first episode is the one in which the lead character, Nolan, and his non-human daughter Irisa are driving along in a wasteland barely recognizable as a future earth. (The earth has been damaged during a prolonged war with aliens, and much of the flora and fauna are no longer recognizable.)
Nolan starts out apologizing about some nonsense with a married woman he didn't know was married... presumably things were hot and heavy with the woman, her husband showed up, and they had to hit the road with little time to pack. His daughter isn't giving him the time of day. He apologizes, promises never to mess 'round with women again, then turns on the equivalent of the future ipod, and puts on the Johnny Cash song, "Jackson," a wonderful, timeless ballad about something men and women have been hassling over for generations. (The song is a duet between Cash and June Carter.)
Nolan starts singing along. Irisa gives him a sidelong glance, starts softening a little, and joins in singing on the second verse. By the end of that verse, enough is forgiven, and they're connected with each other again. We see the love in their relationship, that gets them through things. In about a minute and a half of the first episode, their relationship is laid bare.
All this, without any wasted dialogue or exposition, expressed through glances, a few awkward words, and a song. When I saw this scene within a scene, I knew I'd love the series.
Now, having just finished watching the first season... it was excellent, by and large. The relationships are interesting, particularly Nolan's and his Irisa's.
Some people dislike Defiance, and have been openly critical about it. One criticism is that it resembles Serenity. There is a surface resemblance, but for those who miss Serenity, that's not actually bad. And it's only evident really in the first season.
One newspaper reviewer said the show was incomprehensible. He must have been in a severely altered state when watching it, because I don't think anyone intelligent could watch it without finding it clear and understandable. I suspect he just doesn't like science fiction and can't be bothered to try to get his head around its concepts. No pleasin' reviewers like that.
The partially terraformed earth, built and growing on the ruins of our world, is beautifully realized.
There were a couple of things I didn't like, in the first season. One was the relationship between the human teenager and her alien fiance. It was okay but dragged a bit, and lacked emotional tension, maybe because the girl was written as nicey-nice, endlessly adaptable and forgiving. (Irisa is a far more believable teenager.)
Another thing I didn't care for was the relationship between the mayor's sister, a prostitute, and an alien woman, which moved very quickly from the alien asking her for some sex tips, to seemingly gratuitious excuses to show the two beautiful women in bed. Not having sex, but suggesting it. I have nothing against lesbian relationships, but this one did felt gratuitous and contrived, thrown in to titillate male viewers who swing that way. I'm not objecting to their relationship being lesbian, but I don't like the insertion of sexually provocative scenes that have little to do with the story arc or main characters. I also didn't care for the way their relationship ended, which again stretched credibility. One character meets her end in a way the audience would have seen coming long before; she was portrayed as intelligent, so it's hard to see how she couldn't have seen it coming.
But these are minor gripes. All in all the show is fun, creative and wonderfully imaginative.