The first season is a mishmash of books 1 and 2. Characters from the books are introduced far earlier in the show than they are in the books.
The biggest weakness of the show, IMO, was that it did a poor job on focusing on the core plot element: where is Julie? The books do a fairly good job of explaining to the reader why and where she ended up where she did. In the show, her movements get buried behind other story elements (some of which, again, are book 2 events), and it's difficult to understand why such-and-such a ship is important, why the Canterbury got nuked, who and why killed the Martian cruiser, the derelict stealth ship is important why? etc. etc.
Skater-punk Tom Jane as Miller was great casting. Naomi is a decent cast, as well, and the actor playing Amos is OK too (although Amos is a one-trick pony both in the books and the show). I think that Holden's actor sucks for the part and is more of a little millennial bitch rather than the confident (if too idealistic) fighter in the books.