At about an hour or so into ‘Passengers’, you might start to wonder why this sci-fi Christmas blockbuster headlined by possibly the two most beloved movie stars on the planet hit screens with such lackluster hype and crap reviews. Then the rest of the movie happens and it all makes sense.

‘Passengers’ does quite a bit right and then blows it all slowly and surely. By the time the credits roll, they come as a relief to the disappointed viewers stumbling out of the theater. It’s not horrible, even though you’ll hear it called that, but the movie has sections horrible enough to overwhelm all the good stuff that actually makes up the bulk of the run time.

Chris Pratt stars as Jim Preston, a mechanic who has signed up, along with five thousand other ambitious humans, to help colonize a new planet. The trip will take over a hundred years in suspended animation, but Jim wakes up early after just thirty. He’s alone. There’s no way to get back to sleep. It’ll be 40 years before he even gets a response to his distress call and he’ll most certainly die by the time anyone else on the ship wakes up. It’s not a great situation to be in. For a while, he has as much fun as he can and uses all of the ship’s many amenities to his advantage, including making buddies with the robo bartender (Michael Sheen).

This material plays rather well. It has a ‘Silent Running’ quality, minus the politics but with more emo angst. Pratt has no problem carrying the film on the shoulders of his charisma. He can get laughs and emotion without having anyone to play with. Director Morten Tyldlum (‘The Imitation Game’) shoots the picture with style and just the right amount of chilly indifference to milk out the awkward emotions. The visual effects and sets are impressive (if impersonal). All in all, it plays with almost the same mix of humor, tragedy and sci-fi eeriness as last year’s ‘The Martian’.

Sadly, that doesn’t last. Soon Pratt’s loneliness leads him to suicidal thoughts and he finds salvation only in the pretty face of sleeping passenger Aurora Lane (Jennifer Lawrence). He obsessively reads and watches all the information about her in the ship’s archives. He falls in love and decides to wake her up, even though that will trap her in the same lost fate as himself. It’s a bit creepy, perhaps even a bit rapey in ways that plenty of blogs have already complained about. However, the movie does explicitly address those issues. You might even say that’s what the film is ultimately about. Dismissing it for those concerns is a little bit overblown.

Unfortunately, that’s when the film’s deepest problems begin. Lawrence’s character isn’t particularly well written. She’s more of a clichéd fantasy than an actual human. However, she and Pratt have undeniable charisma and chemistry. Lawrence overcomes her role’s limitations and the movie becomes alternately sweet and tragic when rooted entirely in their relationship. Then somebody else shows up in this wonky sci-fi epic and the whole thing goes to shit.

Revealing who this celebrity cameo is would be an unfair spoiler. It’s amusing casting until the character turns into Captain Exposition to explain and solve all the movie’s lingering dramatic problems. We quickly learn what catastrophe led the ship to this state and how to save it. Everything unfolds in rapid pace and in grand scale, but without many thrills or much narrative satisfaction. It feels rushed and perfunctory. Granted, it’s still all presented on grand, expensive blockbuster scale with lots of pretty visuals. The effects just don’t deliver the drama they should and the human story slowly peters out to the point where it’s hard to give a damn about anything.

This bloated Christmas epic isn’t a massive failure. In fact, at least an hour of whatever Morten Tyldum’s original vision might have been is retained and is not without its charms. However, when a big sci-fi blockbuster fails in the thrills department, something is deeply wrong. ‘Passengers’ is ultimately a failure, but at least isn’t without interest for those looking for some Hollywood sci-fi without “star” or “wars” in the title this Xmas season.