I do think it's cool that they are targeting a cell phone, but the iphone really ramps up the costs. Main issue I have is that it is $230 for the hardware (plus the cost of an iphone) plus an iphone app that you have to get.
I'm not sure how accurate it is at fuel consumption (or what those screens look like), or how responsive it is, it was a little jumpy and behind on the range test, some cars might lag by a second or so from what I saw, I'd be sad to find that out after dropping $230.
You can buy an awful lot of dedicated gauges for $230, that don't jump around
And you can hack them to display whatever you want.