If you want a challenge, then this is certainly it. I’ve done it twice, in the reverse but as a walker, I didn’’t quite make it to the end, so it’s a dragon to be slayed. I’ve seen runners but I don’t know how they get on. There are some awesome climbs over some pretty remote areas of Wales. The last time I did it the weather was awful, visibility on the mountains poor to say the least. Lots of people got lost and added 6+miles to the whole thing.
Newtown Rotary club organise the summer one, their support is good with lots of food and water stations and even a cooked breakfast at one. It starts at 4AM!