The tray is good quality - it doesn't really "self form" in the sense that it keeps the shape of your teeth after first use (which is what I was expecting)... it's pliable and sticks well to your teeth while using the whitener. I'm glad it comes with a little case so you can protect it! I didn't even try the free tray that comes with Watt's Power Whitening gels because they sounded so horrible, so I can't provide any comparison with those.
ONLY thing is that, at first, I didn't know what to do with all the saliva that inevitably collects in your mouth while whitening... but I found that laying back keeps the saliva away from the whitener so it's not so disgusting to swallow AND allows the gel to work at it's without being diluted by spit! =P