In cinemas from Friday 6 February, rated U.
Golden Compass star Dakota Blue Richards takes the lead role as Maria Merryweather.
Mr Fantastic himself, from the Fantastic Four series, Ioan Gruffudd, plays her uncle Sir Benjamin.
Juliet Stevenson is Miss Heliotrope, Maria's governess, and Tim Curry is the menacing villain, Coeur De Noir.
The film is based on a book called the Little White Horse by Elizabeth Goudge, which is supposed to have helped inspire JK Rowling to write the Harry Potter books.
Like the tales of the boy wizard, the book - and film - are packed full of magic and adventure.
But instead of a hero, there's a heroine, the brave and headstrong Maria.
And also like Harry, Maria is an orphan. She has to go and live with with her grumpy uncle, Sir Benjamin, in Moonacre Manor.
There, Maria enters a world of magic and mystery, and learns of the ancient curse threatening to destroy Moonacre Valley.
From magical creatures to pianos that play themselves, you really do feel anything could happen in the magical world of Moonacre.
There is plenty of action and loads of scary chase scenes - and sometimes you won't believe how brave Maria is.
There are some really funny bits too, Maria's governess, Miss Heliotrope, is hilarious!
And there's also quite a bit of romance, and some pretty impressive special effects.
Dakota is brilliant as the heroine Maria, you'll really be swept along on her adventures as she tries to bring peace to Moonacre.
The magical chef, Marmaduke Scarlet, played by Andy Linden, is great too - he's hilarious, and a bit freaky - all at once!
Any weak bits?
Robin (right) is different in the film
If you're a fan of the book, at first you might be a bit disappointed with the changes the film-makers have made.
The character of Robin is really different, and lots of characters have been left out.
But in the end you'll probably agree the changes have helped make the story a better film.
Hit or miss?
If you like magic and mystery, definitely a hit!
Unfortunately we are not accepting any more reviews on this film, but there are more things to talk about on our reviews page.
"I loved it! It is the best film I've ever seen. I think the book is rubbish. The film is way better."
Georgina, 14, Birmingham, England
"It was an excellent film. I really enjoyed the bit when Maria found out where all the food was coming from. My least favourite bit, was when the..... actually I don't have a least favourite bit. This has been the best film a long time for me!"
Vicky, 11, Harrogate, England
"It's wicked as well as cool and magical. I like this because I like Dakota Blue Richards. I wish she had won an OSCAR!!!"
Nicola, 9, Romford, England
"I think it is very exciting and that Dakota and Augustus worked very well together. Miss Heliotrope is very funny."
Abi, 12, Cumbria, England
"Best film ever! Although the book is much better. I thought Dakota Blue Richards was amazing but I think that Juliet Stevenson and Augustus Prew were the wrong people for the part."
Lily, 9, England
"I liked it because it was fun solving the mysteries!!"
Isobelle, 8, Lincolnshire, England
"A great film for all fantasy fans. Dakota Blue Richards is a very good actress and Juliet Stevenson was HILARIOUS!"
Ally, 14, London, England
"I thought this film was amazing. I loved the costumes and although the script was a bit wooden, the actors carried it off well. It was exciting and at some points a little eerie."
Grace, 13, Glasgow, Scotland
"I really loved this film. Dakota Blue Richards was amazing and Juliet Stevenson was hilarious! I would recommend this to anyone who loves adventure!"
Jess, 12, London, England
"I loved it! I think it was the best film ever, but I liked the book way more."
Molly, 12, Shropshire, England
"I think that The Secret Of Moonacre is an excellent film. However, it didn't stick to the book very much."
Rhiannon, 11, Dorset, England
"Dakota Blue Richards has proved to be an excellent actress! I loved it and now I'm desperate to read the book!"
Megan, 12, Neath, Wales
"This is a great movie that is based on a brilliant book - it is also one of Dakota Blue Richards' best movies EVER!!!"
Ciara, 12, Coleraine, Northern Ireland
"Adventurous and funny. I absolutely loved it, well me and my Mum did. My Dad and my brother nearly fell asleep!"
Maya, 9, Bromley, England
"I wouldn't recommend this to my mates but I think if you're an adventurous person you would probably like it."
Leila, 9, London, England
"It's a great story and film! I loved the funny characters and it was very good! The only bad thing was Dakota Blue Richards, personally, I don't think she can act very well."
Emalie, 13, Hampshire, England
"I thought it was great and I am a huge fan of Dakota Blue Richards and I've seen all of her films including the Dustbin Baby. She's brilliant!"
Emily, 12, Nottingham, England
"This film has completely ruined the book. I will admit that Juliet Stevenson was funny but it wasn't enough to change my view that this film wasn't as good as the book."
Jenny, 13, Cheshire, England
"I thought it was brilliant and one of the best films I've ever seen."
Emily, 11, Nottinghamshire, England
"I think it's a brilliant story. I want to see it over and over again, everyone should see it."
Alice, 14, Plymouth, England
"Best film ever! I especially liked the old aunt, she was hilarious!"
Tim, 11, Reading, England