This flight ran largely to time (despite an unexplained gate delay at Heathrow). The premium economy cabin is comfortable and more than adequate for a 7 hour flight. The cabin crew were efficient, although not particularly welcoming. The food choices were limited, but the quality of what was offered was perfectly acceptable - nice that in premium the food is served with proper tableware.
There were a few penny pinching niggles. The supplied headphones were truly appalling in terms of comfort and quality - ensure you bring your own. In flight entertainment was really poor eg compared to BA or Virgin in particular. The drinks service was also quite limited.
I would be happy to use this route with Air Canada again, but they could turn a good product into a great product with just a few minor changes that need not cost them too much.