The Bush Creek trail is cruisy at the top. Further down it turns into a little adventure trail with lots of creek crossings, some mud, some short steep pitches and some interesting switchbacks.
It is not a purpose built singletrack so you won't find rollers, swoops, jumps and so on but it is more or less down-slope all the way. It's nicely varied, sometime open, sometimes in forest, sometimes on grass, sometimes narrow, sometimes wide.
Most riders on it have come down the Slip Saddle trail from Coronet Peak although you can ride up and back from Arrowtown.