Something that all the hated-it reviews have in common is that the reviewers either (a) read the books, or (b) felt the movie had no resolution. Well, I didn't read the books, and I enjoy films without clearcut resolutions (meaning the viewer has to actually think a bit), so I decided to have a go at it. If you're like me then read on.
"Riverworld" is a SciFi Channel production which means you get to see a lot of SciFi veterans gracing the screen (3 from Battlestar Galactica), a lot of Vancouver scenery, and some made-for-TV special effects. Just don't expect a zillion dollar budget and Marlon Brando. You can definitely expect to be entertained in a very creative, action-packed way. By "creative" I mean where else can you see a movie with blue people, samurais, spaceships, Mark Twain, conquistadors, the Chechnyan War, lawyers, crossbows, zeppelins (not the Led kind, but it wouldn't have surprised me), gods, robot horses, and did I mention Vancouver?
Without spoiling the fun, I'll just say the story is about a reluctant hero who gets dropped into a game that will decide the eternal fate of humankind on some alternate world where life & death don't necessarily come in that order. Nothing is really spelled out for us, and that's what keeps things interesting even though the rest seems like a clearcut battle of good guys vs. bad guys. In other words, there are likable characters and loathsome characters, but we don't exactly know who's fighting for which side, nor do we even know exactly what each side wants to accomplish until nearly the end (and even then a lot is up for interpretation). The ambiguity raises the bar from an otherwise ordinary scifi adventure to a moral and philosophical mindbender.
As far as entertainment value, I was impressed with some great swordfighting, a very interesting love mystery, vivid & very human characters, and the whole feel of an epic adventure with no rules. Although it's a futuristic science fiction, it has a lot of throwback elements and a great backstory of warring gods. So in that respect the story is along the lines of the great classics "Stargate" and "The Prophecy".
The scenery is just stunning, an epic journey up an endless river that figures in as prominently as any of the characters. More than once I was reminded of Herzog's "Fitzcarraldo" and "Aguirre, the Wrath of God", two surreal adventures set on the savage, endless Amazon. But in this case the scenery and soothing Pacific Northwest setting contrasts against Herzog's cosmic chaos with nature's tranquility and majesty.
It definitely got me interested in reading the Riverworld novels, but I've been told that's a sure fire way to hate the movie, so maybe I'll just leave well enough alone. If they ever do make this into a regular TV series I'm sure I'll be a fan.