I regularly eat here and bring friends and family here for meals (probably 4 times in a year, winter, summer, lunches, peak times, quiet times) so I have seen enough to form an opinion of consistently good food and service. Nice location, super views, pleasant grounds (when it's not raining!). Pleasant, helpful staff.
Only gripe on this occasion was having to phone 3 times before someone picked up the phone to take a reservation.
The evening menu is one of those menus where everything is appealing and it is difficult to choose. On this occasion, although we were early enough to have the early special fixed price menu (before 1845), the dishes were a little 'plain' so as we were celebrating, we chose from the main menu.
All the food was hot, tasty and well worth the money. Vegetables were provided with the main course and everything was eaten.
Wine list is fairly comprehensive and reasonably priced ('house' white about £17 per bottle as I recall). On this occasion, my glass of wine came in a glass with lipstick on. This was replaced swiftly. Also there was a confusion between a glass of Pino Noir and Pinot Grigio, which when pointed out to the waiter was quickly sorted out.
I will continue to eat here. It is part of the local (to this part of Scotland) chain of Costley & Costley. If you fancy a meal that is of excellent quality but without the formality (shirt and tie) of Lochgreen House, then Highgrove House is for you.