Looks like a decent alternative for some folks, if you can score for free from somebody like a bar owner or something getting rid of them. Don't know that I'd pay 60 new for something thats going to have an unknown life cycle. Also would worry about sanitation over time if the inner lining is plastic with scratches or whatnot from cleaning, but with cornies being ever more expensive and a pain in the posterior to find, glad somebody out there is trying to come up with new ideas.
Edit: Also, looking at how these assemble now, seems like you kind of get the worst of both ends. Not enough of an opening on that inner PET bottle to really get all the way down in there if you need to like in a corny, and they also have a notice saying that you can't use standard commercial keg cleaning equipment through the sanke connection like you would on a stainless keg. I guess if they sold the inner bottles for a cheap price and you could just toss those and replace if you needed to that would help. Again, happy to see folks trying to come up with new ideas for the industry.