It’s best if you open the link to the social card game on a phone: while the app opens on Facebook for the PC, too, it’s not playable (tap commands, for example, don’t work). You need to access Facebook through the smartphone browser (not the Facebook native app) in order to play the game, which will be opened in a separate browser window.
I just gave Legend Cards a spin, and so far, it looks like gloops did a good job translating the game: I couldn’t find any weird grammar or other mistakes that might put English-speaking gamers off. On Wi-Fi, loading time was very short, for example during battles with other Facebook users or when starting quests.
It’s the company’s first social game in English, and I am eager to see how well it will do outside Japan (where it is available on Mobage for feature phones and smartphones).