If you put this into comparison with anything else in the anime, it falls pretty short. At first I was really confused why it was released when it was, but the end of it makes sense now - it would have spoiled so much.
Some new characters were introduced, so I'm hoping that S3 sheds some light on them. That's the biggest piece I got from this.
If you enjoy the series, you won't be overly disappointed, just don't expect the same that you get from the full seasons.