If they haven't changed the course this year...
the first mile is on-road and mostly gently downhill (I think...)
then it's up a farm track, across a footbridge which is only 1 runner wide and causes a bottleneck, across fields, some grassed some planted and hence muddy, down another farm track (wet and rutted), onto what I guess is the floodplain of Piddle Brook (sort of water meadow, a bit squelchy) then back up to the finish.
It's not a killer M/T race, just a nice run in the countryside. If you're going for a time (which I'm not) get a fast start to avoid the bridge queue...