I think the appropriate comparison is to look at alternate technologies. Don't look at conventional crude oil, because we don't have that available, and don't look at normal natural gas. The two comparisons I like to make are to coal, which is abundant in western Canada and western United States, and the other would be ethanol from farming operations.
In the case of coal, the oil sands are much cleaner in terms of carbon emission, and much more efficient from an energy perspective. To make liquid transportation fuels from coal is much worse in terms of the energy balance.
The other comparison is to ethanol. The current ethanol plants in the United States and in Canada get about 1.25 to 1.4 units of energy for every unit of energy put in. Most of the energy put in is from fossil sources. So their yield of energy is actually much worse than from the oil sands. The difference, of course, is when you burn a litre of ethanol, that carbon is from plants and not from fossil fuels.