I can see the benefit of the double sealed valve to ensure no odours (or anything else) leak out.
However the review mentions that the tanks benefit from one piece construction and - as I have never owned a product like this before - wondered what that brings to the party since it isn't made clear. Do other portable toilets have to be disassembled and cleaned out, or is there a danger of spillage through the seams, or what?
Are these practical to take canvas camping then ? My teenage son & I like to pop off together for odd weekends but he hates the prospect of going to toilet blocks if nature calls during the night, usually because they are at the other ends of the sites.
Yes, definitely, assuming you have space to put one in your car / tent. I personally use a separate toilet tent (eg like this) , but if you're not shy you could just pop it in your main tent somewhere or a spare bedroom inner if you happen to have one!
We used to have one of these when tent camping. I wanted something for emergencies/nighttime but didn't like the idea of a bucket or something you had to empty every day. The Portaflush worked really well and didn't take up too much room in the car because its fairly small.