As for how well the show's visual style translates onto the Wii, Beasts of the 5th Sun does an adequate job. While the videogame doesn't quite match the smoothness found on the Cartoon Network series, it uses the system's capabilities quite well in order to provide character models that while a bit blocky, are by no means tough to bear. Outside of the human characters (the Saturdays and some of the enemies), the other character models (mainly the cryptids) also stack up well compared to their TV series counterparts.
The other side of the game's presentation, audio, gets the job done as well. While you won't find yourself humming any of the background tunes or thinking the game's dialogue is superb, it does a good job of conveying the game's story (where the dialogue is concerned) and action (in the case of the music), and never really gets annoying. In fact, I was quite pleased to notice that Zak Saturday's one-line retorts were fairly low-key, which is always better than having too few voice-clips and having the statements get too repetitive. As for the voicework itself, I'm told the actors from the series have reprised their roles for Beasts of the 5th Sun, but there is nothing in the manual to indicate this.