One of those cans costs 88p in Tesco but they're currently on offer at 50p in Asda. That means the product you've linked to is, in my opinion, rather expensive!
ah yes, i was just looking at the sze of the can in the mans hand which looks quite big...but its actually got a layer around it for the heating so its probably just a normal tin
I emailed a friend who is into outdoor stuff. He says he was aware of these 40 years ago but has never tried them. I imagine they will have had several 'new & improved' recipes since then.
If I were stranded in a remote country and had the option of one of these or catch my own dinner, I might be glad of it. Otherwise I think I'll give them a miss ;-)