I have the Undercover Flex.
Not impressed with the finish/attention to detail. There are beads of sealant showing on the exterior of some of the rubber seals, the rod & lever lock on the third panel is very flimsy, if the long rod (passenger side) is not perfectly aligned with the rails the whole rod bows out and it doesn't lock under the rail. Lots of sharp edges on the sheetmetal brackets and the rail caps aren't sealed into the rails. All these things would be easy to overlook in a lower priced product, but for $700+ I would at least expect them to have someone wiping the excess sealant off the exterior seals.
As for functionality, its easy to open/close, and only took about 20mins to install. I did have to get softer tubing for the drains. Seems to be pretty watertight, a decent day of rain and a pretty thorough washing and there was only a bit of water at the front of the bed where it leaked between the rail and the end cap with the drain fitting (a bit of silicone should solve that). It did take about 2 days of 40°-50° weather before the bedside seals relaxed and laid completely flat against the rail caps.