Ok I have now engaged my brain and realise you mean the Edinburgh
to St Andrews ride:
http://www.lepra.org.uk/articles.asp?article_ID=100 rather than it being a ride in Edinburgh on St Andrews Day as I had thought

Sorry.
Anyway, yes I have ridden the route a few years ago. It can be as easy or are difficult as you make it. I was in a hurry when I did it as I was being collected by Mrs Noodley at the end so did it fairly quickly and probably made life difficult for myself rather than enjoy it to it's full.
But there is no need to rush it as there are plenty of opportunities to stop en route (there is even an ice cream van at the top of Cleish climb). The hills are mostly long and draggy but not difficult but there is one short climb which goes up very sharply. I struggled to the top of it and reckon I would probably walk it now given that I am nowhere near as fit as I was then
It's a really nice ride taking in a lot of different terrain from urban city centre to the Forth Road bridge, semi rural Fife, rural Fife and finishing beside the Old Course clubhouse. I'd recommend it. There were all sorts of bikes being ridden, and families riding together as well. I'd imagine the route is a bit more difficult than Pedal Scotland route but not greatly.