I'd disagree - it's not 'garbage' but certainly not the best either. The ridiculous claims about how long it lasts for are also well off the mark. Particularly as many of the people who use this are also the sort to clean their car using Fairy liquid and/or use garage machine washes which strips off EVERYTHING.
The main thing though which is a joke, is the cost. I used to work as a valet at a dealer site and even 10 years ago we were charging around £400 to supply and apply this. The kits cost about £40 (or did then) and took about 3 hours to do, an hour or so was just waiting for the second stage paint protector to cure.
Overall - I'd say sell it if you have a kit and use the money to buy yourself a decent hard wax if you want long lasting protection.