By Genevieve Hassan Entertainment reporter, BBC News

After a six month viral marketing campaign that has kept fans guessing, Cloverfield is about to be released worldwide. But does the "movie for the YouTube generation" live up to its hype?

The film has been shrouded in secrecy

It all began in July 2007 when a trailer showing a huge New York explosion and the severed head of the Statue of Liberty crashing to the ground was first shown before screenings of Transformers.

Appearing to look like home-video footage, the film had no name. A US-style date, 01-18-08, appeared on the screen. It left cinema-goers intrigued.

What followed was a media blackout on details about the film, together with a viral marketing campaign not seen since horror film The Blair Witch Project was released in 1999. It sparked almost a global obsession to try and discover the film's secrets.

It adopted the working title "Cloverfield", giving nothing away and adding to its mystery.

Excitement

When it was revealed that JJ Abrams, creator of TV shows Lost and Alias, was behind the project, the excitement built up.

It's a monster movie for the YouTube generation. Director Matt Reeves

Fans were expecting something big - and good.

The film was so shrouded in secrecy that scripts were watermarked to prevent anyone copying them, and each day producers would swap the latest pages for those of the previous day.

A cast of unknowns were hired for the film and were not told what they were signing on to, or auditioning for.

Film fans trying to find out about the movie ended up at a series of fake websites set up containing cryptic clues to other websites.

But after all the hype and build-up, has Cloverfield met expectations?

Reviews

Director Matt Reeves is confident of success: "No one's done anything like this before. It's a monster movie for the YouTube generation."

The film follows a group of friends as they are caught up in an attack on New York City and their attempt to escape and survive the carnage.

Unknown actors Michael Stahl-David and Odette Yustman were cast

Abrams said he wanted people to "live through their wildest fears" during the film.

After its US premiere, the initial reaction has been mainly positive, with reviews commenting on the potential downfall of the camera technique.

"The first thing you need to get used to in Cloverfield is the potentially nausea-inducing shaky camera work," said the San Francisco Chronicle's Peter Hartlaub.

Associated Press reviewer Christy Lemire wrote: "The Blair Witch technique does grow dizzying, but it's effective because it feels so authentic and gives the movie an interactive quality."

But most reviews are encouraging movie-goers to see the film purely for its entertainment value.

"Cloverfield is a fun movie. Plain and simple. It's sit back, relax and go. It's a rollercoaster ride," said Peter Sciretta from website Slashfilm.com.

Considered to be the pioneer of viral marketing, The Blair Witch Project cost just under �13,000 to make but raked in more than �125m worldwide.

Cloverfield has been made with a modest budget of �15m, but box office receipts will soon tell whether the film has been a successful exercise in marketing strategy, or a letdown after too much hype.

Cloverfield is released in the UK on 1 February