Anyone know it / ridden it? I'm asking for Dee's friend .... I'm assuming it's fairly flat and easy going?

Any input most welcome.

Yup - mostly on a disused railway line with a good dust surface and easy (no) grades; plus a few sections of dedicated trails, also good surface with some minor ups and downs.

Cheers Phil.

As Phil said, mostly flat with the exception of the bits where it doesn't follow the original railway route, notably the section through Scolty Forest and the evil bit round the back of Kincardine O'Neil that lobs in a big hill to avoid the road. Overall though, it's a very pleasant ride with lovely Deeside scenery at times.