I did it last year. Signed up for the 2 day one but only made it to York :-(
It was well organised and signed. I found the pit-stops to be poor though. They were just crisps, flapjacks, bananas etc. That’s OK for a short sportive but 220 miles in a day I really needed one that had jacket potatoes or something savoury and filling.
Drop-out rate for ‘experts’ was quite high (despite what they say on the website).
I didn’t set off on the second day because I had real knee pain. The last 50 miles to York was tough, shooting pains in the back of the knee. This was all sorts of mistakes that I made – possibly seat slightly too high, possibly ITB issues. Took me a fair bit of physio to sort but anyway.
If you’re thinking of doing the 2 day one, make sure you get some decent mileage in before hand. It’s tough and not a lot of fun, but a great achievement.
The guys doing the 4 day one looked like they were having much more fun – finishing early, a few beers, time for food etc.!