If you're not a dedicated reader, SyFy's TV Expanse series is a more accessible entry into the series, though I'd rate it alongside the excellent Night Watch, as show where movie viewers do benefit from reading the books first. It is faithful to its source material, to boot. (RANT: Marvel (of late) and Game of Thrones have shown the way, after a century of scriptwriters botching the conversions, that following the source material IS the best way. It's mere intellectual arrogance. The screenwriters/directors want to show they can do a beloved, bestselling book better than the actual author... ...and wonder why audiences don't embrace it to the same extent....)
The Expanse stands heir to series like Battlestar Galactica and Firefly.
I was very pleasantly surprised at the quality of the production.
.TV Show - So how is it?
The Expanse, for me, is the best sci fi series since the reimagined Battlestar Galactica (with 100% less self-indulgent navel gazing), and channels the much-lamented Firefly in a more serious way within a more epic, connected, overarching plot. It is well acted (yes, SyFy?! what the heck?), and sensibly paced. It might be a little dense and confusing to those who have not read the books. Like the books, it has deliberate pacing and takes a while to "ramp up." I'd give it until episodes 4-5 before you make a final judgement.
The world building is excellent, consistent and well-realised, the special effects solid without being flashy, and the space combat was very cool - vector movement was prominent with ships being spun to use their main drives, with gravity on the crew having an major impact, as well as the time to reverse course. The sci fi is relatively hard, but well done. Railguns, missiles and massdrivers were impressive in an understated way, and has inspired me to get painting more space miniatures. The limited stealth (absorbing heat and energy but having to vent it after a while) was very interesting as a gamer, giving a submarine-esque feel to the few stealthships encountered. Have to update my own space house rules. The ragtag crew eventually get their own ship - the Rocinante - basically a badass small gunship/PT boat style ship festooned with gatling guns - which makes the Firefly look the like the old merchant scow it is. However it is a movie more about epic plot arcs, characters and a rich setting rather than flashy space combat - so if you are only wanting pew-pew maybe check out Youtube clips instead.
Overall, a well-plotted, thoughtful series which has an understated quality I don't really associate with SyFy. Rapidly climbing to be my current favourite TV series, period.
Books - worth the effort?
Yes, well worth the effort, but as they are hefty tomes, recommended only for dedicated readers. The author "James Corey" is the pen name of Daniel Abraham, a very talented fantasy writer known for his excellent prose and rather slow-burning style, in collaboration with GRR Martin's assistant Ty Franck.
A thumbnail sketch: A Firefly-esque bunch of ex-miners lead by an idealistic captain and smart-mouthed crew discover a derelict ship - and a deadly secret. A world-weary detective is tracking a missing girl. Galactic conflict ensues, and a terrible threat to humanity is revealed.
The Expanse book series features excellent writing, and a well-thought-out plot, setting and characters. Space opera meets noir detective thriller. Characters have tough choices - and sometimes make wrong ones. A word of warning - It's 600 pages long, and the pace only picks up in the last 50 or so of the first book, Leviathan Wakes. Though it was well-written, I wasn't as invested in first book as I thought I would have been. I feel this series only really kicks off with the sequel Caliban's War - and that's a huge time investment.
Probably the best sci fi book series in recent memory, behind Ann Leckie's Ancillary Justice series (which edges it on strength of shorter, more accessible books and a more unique core concept rather than writing style).
Watch the TV show. It is excellent, but give it a few episodes to warm up. The books are likewise excellent but a significant time investment given the slow and careful pacing, but a must-have if you are a sci fi afficiando.