Vampire Knight Guilty is a continuation of the anime Vampire Knight, and that is all it is. It is not its own series, and it is rather unwatchable without watching the primary series.
As for the anime itself, it is absolutely one of the superior ones out there. The plot is exceptional and it has an inimitable outlook on vampires. Each episode ends with a cliffhanger making you fancy to gaze at the next one in the series without delay. Although there is awfully minute action, the drama is what keeps you going, so if you want an adventure shounen where the main character progresses physically, go off and watch cartoon network.
