"Return To Rainspell Island" is based on the popular Rainbow Magic book series. Specifically it is set after book 7 of the series (Heather the Violet Fairy). The plot has best friends Rachel and Kirsty going back to Rainspell Island where they first met in the books. There they are once again called on to save Fairyland from Jack Frost who is intent on conquering it with an army of snowmen.
This is a highly enjoyable movie for both fans of the books and people who just enjoy light-hearted fantasy. Rachel and Kirsty are likeable and engaging characters and the movie's overall tone is sweet and uplifting without ever feeling overly saccharine or sickly. The anime-style animation is excellent and suits the characters perfectly. The voice acting is also very good.
Some fans may dislike the fact that the movie has some strife between Rachel and Kirsty (as opposed to the books where they never argue). While I respect this view, personally I don't see any problem. The tension between the girls never amounts to much, they never have any major falling-out, and is resolved well before the end. Plus, isn't it a good lesson for children to know that friends can have disagreements and still remain friends?
In short, I loved it and I very much hope that there will be more Rainbow Magic movies.