Rating: 4 / 5
I have found them to be quite effective in the Sierras the past two summers.
I have a Bearikade Expedition, and if you're not careful, the metal edges around the latches can slice an OP sak when you put it in or take it out. Consequently, I won't use them in the can. An Ursack could be an entirely different story.
I use them for trash bags and to hold any extra freeze-dried meals that won't fit in the bear canister. At night, I leave them out on the ground, away from camp and the bear canister. I've watched bears walk right past them (in the dark) and never notice them; wouldn't try that during daylight hours when they can see it.
Bear canisters are (supposedly) impervious to bears so I don't care if they are not odorproof. I put my canister away from camp in a spot where Yoggie might find it, but can't roll it away if he does.
The smaller OP sacks make fair dry food containers, but they don't have the puncture-resistence of the Aloksaks.