I read Neil Gaiman's book "American Gods" many years ago. I remember two things about it: I didn't much care for the book, and that I thought it would make a great film. I think this series is the film I was envisioning.
As someone with training in both theology and philosophy, I find the ideas that drive the series fascinating, though not in the way that some might suspect: the idea that gods are created and sustained by worship is ancient. In the Indus Valley thousands of years before Christ, worshipers believed that the smoke of their offerings sustained the gods and the world. Today, the same notion is a staple of science fiction. Rather, it is the examination of the relationship between believers and their gods that I find fascinating, for it reflects directly upon our relationships with today's gods and idols as well. These relationships, and the forms they take defines the difference between the series' old gods and new, and represents the core of the conflict between these sets of gods, and the conflict between the human characters as well. This conflict also represents the appropriately subtle social commentary of the series as well.
There are enough fantastical action elements to keep almost any special-effects dependent viewers happy, while at the same time there are ideas and conceptual flights more than sufficient to allow for a more cerebral engagement as well. I would think however that any viewer who fears the possibility of having their religious sensibilities offended is indeed likely to suffer such an offence. This show's fundamental assertion is polytheism, that is, the existence of many gods. Further, gods are corruptible and in a limited sense mortal. They can and do die, either at the hands of other gods or through human inattention. If you can get past these elements, you might be surprised to find that the series is still remarkably respectful of human faith, but it is a respect granted many kinds and forms of faith. Two further warnings: the squeamish may be made more than a bit uncomfortable by the violence evident in the series. Blood and wounds are fully shown. The camera doesn't linger, but it does not shy from suffering. Secondly, there is an embrace of a range of human sexualities as legitimate forms of religious expression. This results in a fair bit of male and female nudity.
The acting is superb, the direction more than competent. Production values are very high: sets, costuming, and special-effects are all first-class. The network has placed significant resources in the hands of the producers, and we as viewers have been well rewarded for their efforts.