While it has its moments of memorable wit and some appealing rhythmic Broadway-pop songs, “Bring It On” is by no means in the same league as those musicals [Next to Normal, In the Heights, Avenue Q], and has the feel of a daffy lark embarked upon as a summer-vacation goof…It’s when the cast members drop the bonding and the mean-girl bitching to take part in Mr. Blankenbuehler’s exciting cheerleading routines, arranging themselves into dazzling human starbursts, that “Bring It On” really brings something fresh to the ever-expanding roster of shows aimed at the teenage demographic.