I was lucky enough to be able to view Professor Layton and the Eternal Diva at an anime festival. The film was dubbed, though the titles and credits were in Japanese. Obviously this won't be the case for the British DVD release version, but the titles and credits were beautiful and reminiscent of the game's titles and credits. The animation was exactly as it is in the games, and despite its cartoonish simplicity, it looked spectacular on the big screen. Elaborate CGI for more tricky sequences did not look out of place next to the flat characters and scenery, which is a relief more than anything.
If you've ever played a Professor Layton game, you might be wondering how they manage to incorporate the puzzles and gameplay elements into the film. Not wanting to spoil it too much, let me assure you that the way the first obvious puzzle is introduced will bring a smile to your face. Don't worry too much about solving the puzzles; the trivial ones you'll get within seconds. The important plot points you might guess, but the story manages to stay exciting and entertaining all the way through.
As with the games themselves, the movie's story is captivating and beautifully animated, with plenty of laughs and gasps to be had. The audience enjoyed the screening so much that there was loud applause once the credits had ended. Since the film deals with dark topics - death is a big factor and plays a big part in a very symbolic fashion - very young children may not understand or enjoy the film. There were very small children at the screening, and every so often you could hear them asking in confusion what was happening. They did not seem to understand the symbolism and were often puzzled by certain characters. However, though the action sequences are relatively intense, the children did not appear frightened by them. It's very much a case of "your mileage may vary" as far as showing the film to children is concerned.
The voice acting is a little tricky to describe. Luckily for us, it was Maria Darling as Luke, as it's supposed to be for British audiences. Just as well, really, as Lani Minella's Luke is simply atrocious. Christopher Robin Miller is wonderful as always as Professor Layton. The rest of the cast is somewhat hit-and-miss, many of the supporting characters sounding very American-pretending-to-be-British. This doesn't actually make the film any less enjoyable though.
All in all, it's a beautifully animated film with some superb voice acting and a captivating story. Whether you're a fan of the game or not, this is perfectly viewable and enjoyable. Do give it a watch - preferably while drinking tea.