Here is a link to some reviews about Air China.

http://www.airlinequality.com/Forum/air_china.htm

Their website has no explanation about their classes, their seat pitch in C class is only 42 inches, just above or same as some airlines economy plus product.
For Vancouver they are using a 767, which I am sure is won't be one of the first planes to be re-fitted with new Business and First Class product.
Transiting in Bejing doesn't seem to be an easy experience either.
I would also re-think and choose another carrier.

I think that China Air (Taiwan) has done a lot to improve their safety record and seems to be quite respected now by many travellers for their service standards.

If you are thinking about Air China, considering their not so good C class product I would seriously consider EVA Air in Evergreen Deluxe class out of YVR. Transiting in Taipei is easy and comfortable and their service is quite good. It's not Cathay Pacific or Singapore Airlines but it's good.