Life on Mars USA's run on FX is halfway done now, so perhaps I'm premature in offering a verdict, but it's still worth offering some preliminary comments.
Firstly, it's actually got more to recommend it than I thought. My expectations were pretty low based on the fan grapevine, but I thought, give it a chance. And I have to say that there's some snappy dialogue, some good performances, and some takes on particular episodes which can be better than the original (the episode where Sam meets a younger version of his black colleague came across to me as massively patronising in the British version, but not so here). I also find that, having spent my Seventies childhood in a big North American city, the imagery has more resonance for me than the British version (although interestingly, I find that the imagery of Ashes to Ashes has powerful resonance for me despite the fact that the Eighties portion of my childhood was spent in the same city; perhaps it's a big-city thing, since Ashes to Ashes is set in London, not Manchester). For me, the Seventies was about New York style, big afros and flowing dresses, Three Dog Night, and hot summers with picnics in the park, not about strikes, test pattern girls and football games.
Where I'm finding it falls down is in the relationship between Sam Tyler and Gene Hunt. As Sam, John Simm had a kind of trustworthy, sensitive-man quality, where Philip Glenister played Gene as a bluff, blustery man who was clearly compensating for some kind of inner pain; these, coupled with the heterosexual chemistry between the two, made it perfectly understandable why Gene would be willing to go along with Sam's crazy hunches, and/or why he would sometimes unburden himself to Sam at times of trouble. However, the American Sam is too much the classic strong-jawed, blank-faced hero to seem like the sort who inspires confidences from macho superiors, and Harvey Keitel, while lovely, plays Gene more like a bluff, spunky old man refusing to change in a transforming world than someone with any kind of interior turmoil. As for the heterosexual chemistry, there's more between Gene and Ray than between Gene and Sam.
Poor old Chris is just completely marginalised in all of this, coming across as a non-character rather than as a prototypical sensitive man forced into a macho mould.