I have a few. They have some improvements over the Vivi Nova's. Larger capacity, metal-to-metal tube/endcap connections, polypropylene tube vs polycarbonate.
Easy fill just like the Vivi's. The mouthpiece is plastic; there's at least one instance where it melted with a strawberry lemonade flavor.
When compared side by side with the same juice in a cartotank, I have to give the edge to the cartotank. I've got some juices that if I didn't know what flavor it was, I wouldn't know because its so muted.
You do need to make certain that the endcaps are completely snug, or you may note some juice weepage. I noticed this when I saw "perspiration droplets" on the tank. No cracks in the tube, but the endcaps weren't totally snug. Since discovering that and making certain the caps are tight, I've not noticed it anymore.
I don't own any Vivi's to make a direct comparison.