Been twice - once for a work thing, totally unimpressed but we were quite a large party so gave them the benefit of the doubt. DH and I went for a very big wedding anniversary and it was sooooo disappointing.
I had oysters Rockefeller as a starter and the oysters came topped with a splodge of uncooked bechamel and a raw spinach leaf. They should be served with a lovely, hot, bubbly spinach and cheese gratin topping. The oysters were ok after I scraped the 'rockefeller' off.
I had a steak as a main course
It was as tough as old boots (ordered rare), brought on a plate accompanied by a marrowbone sliding around the plate - really bad presentation. The sides were all extra £4 for a tiny copper pan of peas and £4 for 6 chips. Outrageous 
.
It's all style over substance - they rely so much on the tourist market, and yes, the interiors are atmospheric, but food quality? Nope. And the wine list is massively overpriced - a wine we love, and order at a favourite local restaurant for £28, was £48 at The Witchery.
Rhubarb at Prestonfield is much better (although a little way out of town).