The Victoria Park tracks are for those who like it steep and ugly! There are several serious downhill trials in the park that you probably won't want your cross country bike near.
Actually, there is quite a bit of variety. The track map on the Christchurch City website (google it) lists two easy trails, four intermediate, five advanced, two expert, and six extreme.
The park is not very visitor friendly - its hard to find your way around even with the map but there are signs here and there. One track that is easy to find is Brake Free. It's a short and sweet intermediate trail. It will probably lead you into Sesame Street, a twisty, jumpy advanced trail that won't try to maim you.
There are jumps all over the park. If you love air you'll be right at home...