Hi tidgy
It's a lovely walk with great views along the way. Rowlee Pasture and the paved path do seem to go on...and on...but it's well worth the effort when you reach Alport Castles.
If you have flexibility, it's best to pick a fine, dry day to do the walk....if only to ensure you get good views!
The weather can be pretty miserable up there during the Winter, with low cloud/drizzle/mist often obscuring any decent views of the 'castles' and the 'tower'.
On the plus side, there is a bird hide right on the edge of the Castles, which can double up as a bad weather shelter. I've had my lunch in there and a break from bad weather more than once!
Hope you enjoy it!
Tracey