I've not stayed at this site but I did pass it when staying at New England Bay for 2 weeks last summer. The site is in a beautiful setting with views overlooking Port Logan bay. It is a sleepy but very pretty spot - I spent a long time taking photos of the harbour. I imagine the site could be rather exposed if windy as it high up and there did not appear to be much shelter.
The whole area is a beautiful and unspoilt. I would strongly recommend New England Bay too.
I love Dumfries and Galloway.