Being geographically challenged (yeah, I'm in the wrong region and my local SyFy isn't going to carry it for some time I suspect), I find it difficult to view the series; however, the kindness of friends allowed me to view the pre-broadcast S01E01.
Hooked on the novels, I was eagerly anticipating the screen adaptation, hoping that that the grittly 'realism' of the novels got into the production edit: I was not disappointed. Many Sci-Fi TV shows neglect the environmental aspect of the filming, preferring to spend money on character appearance and story lines. The Expanse seems different: unlike, say, B5 or Star Trek, dirty areas are /dirty/ (more like The Red Dwarf), they don't look like they've had an 'Acme Dirty Space Station Kit - 25% Extra Free Litter!' applied.
The CGI is also pretty damned good: the visuals aren't crisp and sharp, looking obviously computer generated; you get a sense of scale and distance and fake backgrounds merge into the foregrounds seamlessly - you can't tell where the set ends and the CGI starts.
The novels clearly indicate the differences between Belters, Martians and Earthers; it is a very important aspect of the plotlines - the show also highlights this using Belter creole and good use of CGI to represent Belters (though so far, I haven't noticed the physiological differences between Alex (Martian) and Jim, Shed or Amos, or the differences between Miller and Havelock - though there are very good production reasons for this: it would be too damned expensive! - it doesn't impact the story though, so I don't really care).
It is incredibly difficult to turn a novel into a TV series without losing bits; especially when you've only got an hour of screen time less 25% for commercials - but I think the production team did a pretty good job. They got the salient points into the first episode, even though it detracts quite a bit from Leviathan Wakes - to cram all that into a 45 minute episode would require a 30 episode season, and even then you wouldn't get it all in; it would also become pretty boring to those who haven't read the novels.
As this is a TV show, there are restrictions on the type of content that can be broadcast; the novels are no-holds-barred shit-kicking space opera - some of this stuff could be considered inappropriate for putting on screen, unless it was to be a late-night show, thus reducing audience figures: not a good thing, especially as the larger the audience, the higher the budget for the /next/ season!
I'm hooked already; and I still have to wait another 4 days for E02!