Chris
The bits that are properly off-road are very muddy and slippy at the moment, but there's not that much of them, and the rest of the course is either tarmac, pavement, or hard-packed paths.
in terms of shoes, I think it depends on your trail shoe of choice, and whether you're comfortable doing 7-8 miles on pavement or tarmac in your trail shoe. I'm probably going to wear my normal road shoe for this, and just accept that for about a mile of each lap I'll need to take little steps and look out for the slippy stuff.