It’s an unfortunate reality that the better the effort (film or otherwise), the more significant the otherwise insignificant flaws. I entered the theater with high expections—and for the most part I was satisfied with director Steven Spielberg’s adaptation of H.G. Wells’ watershed sci-fi novel “War of the Worlds.” In terms of technical ability and craftsmanship, the film is a magnificent achievement.

For anyone unaware of the story’s pedigree, H. G. Wells first penned the classic tale of Martian domination and the impending demise of humanity in 1898.

Byron Haskin directed a 1953 film (starring Gene Barry and Ann Robinson) that, in my opinion, remains one of the better ’50s sci-fi efforts. Modern updates, such as “Independence Day” and the campy “Mars Attacks,” are merely variations of H.G. Wells’ original theme of “us vs. the little green them.”

For those anticipating a rehash of the upbeat, CGI-laden “Independence Day”—it’s not.

Spielberg portrays the alien menace in “War of the Worlds” as very real and very frightening, and he channels our fear into a single family’s plight against unstoppable aliens.

Tom Cruise very nicely plays Ray Ferrier, a divorced dad whose two part-time kids, Rachel and Robbie (Dakota Fanning and Justin Chatwin), have been little more than distractions in his life. But a mysterious lightning storm activates a mechanical, tri-legged killing machine from deep underground. Ray’s neighborhood is quickly annihilated and Ray flees with his kids—keeping his own fears in check while coaxing his children (who barely seem to know him) to trust his instincts for survival.

Spielberg’s cameras rarely lose sight of Ray: this is one man’s personal journey through an inexplicable hell. He’s not a scientist or a fighter pilot or anyone who can help stop the onslaught of alien invaders. Ray’s fears are a microcosm of humanity’s—a nice change from the superhero-type mentality that’s been plaguing theaters lately.

I’m not sure why Spielberg wanted Ray to be so unlikable as the story begins, but in a crunch he’s handy to have around. And I did like Cruise in this role. Ray Ferrier is scared, and Cruise’s performance leaves no doubt about that.

For those who simply can’t help but compare “War of the Worlds” with “Independence Day,” realize that you’re comparing apples and oranges. While the latter featured a healthy dose of humor with its ground-breaking special effects extravaganza, “War of the Worlds” is dark and sinister—a cat-and-mouse thriller whose “cat” happens to be from elsewhere, hungering for humans.

Now to the aforementioned flaws in Spielberg’s adaptation. For one, Ray learns that the aliens buried their massive killing machines deep beneath the Earth’s surface thousands of years before—meaning their intent had been to return one day, presumably when mankind had sufficiently multiplied, and “harvest the crop.” But the implication is this: the aliens also had thousands of years to determine the planet’s suitability for their own survival. The fact that these creatures completely ignored any potential bacterial hazard seems to me a rather large lapse in their logic.

Another irritation is Spielberg’s occasional habit of attempting to humanize his characters in the midst of the action. At one point, Ray and his daughter are trapped in a farmhouse basement with a shotgun-toting survivalist (a delightfully crazed Tim Robbins). While the alien menace hovers nearby, the two men bicker over survival tactics and eventually clash, although the clearly bigger threat lurks outside, liquefying human stragglers into a kind of alien fertilizer. Frankly, I’d have preferred attending to the terror outside.

And the film ends too suddenly for my taste, with perhaps a few too many alien threads left hanging. Just what was the function of those blood-red veins overtaking the landscape? Were the aliens here to stay or simply passing by? Were we food or fodder?

Ah, well . . . mostly trivial flaws in the grand scheme.

In a nutshell: This one’s an intense, mostly thrilling look at contact with another species (“E.T.” it ain’t). Cruise is admirable and Spielberg does a terrific job making life on Earth seem all-too-suddenly precarious.

It’s a pretty nifty adaptation of the granddaddy of the alien invasion genre—well worth a look.