I researched these about a year ago, and thought I had found the idea toilet for my situation. Besides the environmental issues, I discovered another one.
Those cartridges are designed for 15 - 17 'deposits', so for someone on an extended trip or with a family of five, that would be fine. However, most of my trips usually end up being just me for a weekend, or maybe a full week.
So, if I go for a weekend and use it 2-3 times, it will sit because I don't want to waste the majority if a $20.00 liner. Now, if I don't go camping again for a month or two, it's really going to get weird. You can't cut the used portion off, because of the octagon base it has to have to make it twist the bag into individual containment pouches.
If they solve that problem, it may be worth considering. It's not the ideal disposable method, but no worse than a garbage bag full of dirty diapers going into the dump.