I don't have one but here are some intial thoughts:

Expensive! At $550, you may find an inline unit on Ebay for equivalent cost, especially if you install it yourself.

Same issue as a floating chlorinator. If it gets stuck in one spot, you'll have a high localized CL concentration. That could be bad for ladders, liner, etc.

Circulation will be poor, so I don't buy the "Reduce Pump runtime by 50%!!!" claim.

The "Saltshock" product really destroys the credibility of the site in my opinion.
From the site:
"SaltShock is a significant part of the SolarChlor system and should be used weekly when water temperatures exceed 70 degrees. SaltShock is an oxygen-based compound specially formulated to enhance salt-water pools and is safe to use on all types of pool surfaces and water sanitizers. SaltShock enhances the efficiency of salt generators and pool equipment." -What exactly is it for $5/pound?? A 40 pound bag of salt is less than that at Lowes.

They don't specify exactly what salinity level you need for a 20K gal pool. They give a range from 3,200-6,000. You'll definately taste the salt at that higher level.

Perhaps one of our resident EE types can tell us if that kind of photovoltaic cell is capable of producing the current required for electrolysis under typical pool conditions.

It may be a truly innovative product, but the website screams "Poolstored" to me. If they'd used a little more class and some more accurate data, I'd be inclined to research it further.

I bet Chemgeek will have a ball with that "Scientific" graph they provide....

Just my $.02.