Attempted 2 years ago and got eliminated after 78 miles. Weather was awful, had brake pad issues (didn’t everyone ?) and didn’t enjoy it at all.
Stubborness made me give it another go last year, weather much better, completed in just under 12 hours and really enjoyed it.
It’s almost entirely off-road but much of it is fire road. However there is a suprisingly high proportion of interesting singletrack and some nice swoopy sections.
Not sure if I’ll do it again this year. 2 years ago I really enjoyed training for it, meant I went exploring and discovered rides from home I hadn’t done before. Last year the training felt more of a chore, particularly with the rubbish weather.