Well, well! I found this opening to be quite great. Normally, I'm not content with intros being out there in the Flash Portal, but this was an outlier. It's finely animated and complete enough to fulfill my expectations for a Newgrounds movie.
The fact that you're drawing the characters yourself instead of using sprites makes me all that much more excited to see a full episode of this series. Keeping in mind that this is merely an intro, I do think it's a bit lengthy. Perhaps once you start making an episode, it might be a good idea to add a "Skip Intro" button for the intro.
One more thing... I think the music you've put in this movie is perfectly fitting. I think it'll be alright if you keep it.