The game's set during the first couple of seasons of the animated series, which you probably haven't watched.
“The LEGO Star Wars franchise is a massive hit with fans, bringing in sales of over 20 million units worldwide. We’re thrilled to extend this experience to LEGO Star Wars III: The Clone Wars, delivering the humour and fun players expect from this award winning franchise,” said LucasArts' big-wig Darell Rodriguez.</blockquote>

The LEGO Star Wars game have been immensely successful thus far. We doubt this one will be any different at all.