Love this run - have done the autumn one before.
It's very well organised, feels very friendly and informal (but don't confuse that for loosely organised because it's very professional indeed).
Personally I love the towpath part of the course more than the road sections, which I find a bit uninspiring, but that's personal view. The mix makes it a bit of a toss up between road and trail shows - I opted for trail this time and think it was a good choice because it was rather wet and muddy underfoot along the river.