I seem to be echoing a number of other reviewers by reporting that we were holidaying on Bute earlier this month and ended up eating three meals here out of our 7 nights.
The Kingarth Hotel is a really nice British gastro-pub, which are few and far between in Scotland. (I love to holiday in Scotland, but I don't go there for the pubs, which are mostly stuck in a 1960's timewarp, serving gassy keg beer in depressing surroundings)
The Kingarth Hotel had draft Youngs and McMullens real ale, both of which were in excellent condition.
The first night we arrived at 7pm as a party of 6 without a reservation, and were told that we would likely have to wait 45 mins for table. As we had driven 15 minutes to get there, we decided to wait, and eventually were seated in 30 mins. Our two subsequent visits were both with a reservation.
We ordered a variety of food during our visits, including imaginative haggis starters, home-made minestrone soup (which my youngest son adored!), liver and bacon, sea bream, steaks and fish and chips.
Everything was nicely cooked and served in generous portions.
We typically got out of there each night for about £80 plus tip for 6 people, including drinks, a few starters, and six mains (two of which were kids meals).
This restaurant is deservedly thriving.