I would not compare this to the phantum, since the phantom still holds the data locally.
The idea behind this system is that you are actually on a terminal like a Sunray or thin client, or using terminal server/citrix web client in your browser. It could work, given you take demands on the line(my last assignment from my office was working for a company that deployed this kind of service for dentists and doctor practices, using exactly this kind of interaction.. but for business applications, the basic system was built in 2000.
However; we had to make minimum requerements on the lines, basic ADSL can not handle it, so you need at least business SDSL for a stable connection, otherwise something as simple as a print job could hang the connection for several minutes. And simple graphics are all it can handle, it's not faster then RDP and that was not build for games, no matter how many third party optimizers you throw at it. If they said they were able to fix that, i'd take it on a free trial for a month or so to let them prove it works. The technology was build for Lan speed, not to be bothered by the ups and downs from the internet.
But even if the technology works, did you check out the concept, you can play the latest popular games that are on the shelves, so then I started to play this game, for whatever reason I do not play it for 6 months and then I want to pick it up again to find out they removed it from their servers because it got too old?
I would find it hard to believe that this could compete with xboxlive or playstation network.