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The film stars Sin City actress Jessica Alba, Britain's Ioan Gruffudd and Michael Chiklis from TV's The Shield as astronauts who gain miraculous powers after being exposed to cosmic radiation.

It opens in the US on Friday and in the UK on 22 July.

The comic book-to-motion picture journey taken by Fantastic Four has been fraught with enough obstacles to make that DNA-altering radiation storm encountered by the Marvel superheroes look like a gentle breeze.

And the end result? Fantastic Four's a colossal snore.

After all the fussing and fidgeting exerted in trying to nail just the right mix of comic book action, comedy and pathos, the movie emerges as a tone-deaf mishmash of underdeveloped characters, half-baked humour and unhatched plotting drenched in CGI overkill.

There are the occasional glimpses of the sort of fun Jack Kirby and Stan Lee had in mind when they cooked up their dysfunctional family of mainly reluctant superheroes, but they're few and far between.

More like Thoroughly Conventional Four.

With its playful, slightly old-fashioned feel, Fantastic Four is likely to work better for families and non-comic book fans than it is for the more usual audience of teens and picky genre purists.

The film stars Ioan Gruffudd and Jessica Alba (centre)

It will benefit from being based on one of Marvel's best-loved properties but suffer from a lack of star power and relative paucity of big effects.

An early action set-piece in which the Four use their newfound powers to avert a disaster on the Brooklyn Bridge works well.

But elsewhere the movie makes do with less impressive flashes of CGI work, while shots of Mr Fantastic using his superpowers sometimes make the film seem incongruously like a live-action version of The Incredibles.

In an era when movies based on comic books have become increasingly solemn and serious, this one is content to be trashy.

Compared with the psychological probing and spiritual brooding of Batman Begins, Fantastic Four is proudly dumb, loud and inconsequential.

With its clumsy rhythms and indifferent acting, the movie is more like a television pilot than a big-screen epic.

These days, though, television is probably too smart for a lowest common denominator product like Fantastic Four, which is fantastic only in its commitment to mediocrity.

The really good superhero movies, like Superman, Spider-Man 2 and Batman Begins, leave Fantastic Four so far behind the movie should almost be ashamed to show itself in the same theatres.

The Shield's Michael Chiklis also appears as 'The Thing'

It's all set-up and demonstration, and naming and discussing and demonstrating, and it never gets on to telling a compelling story.

Sure, there's a nice sequence where 'The Thing' keeps a fire truck from falling off a bridge.

But you see one fire truck saved from falling off a bridge, you've seen them all.