I'm sure it'll be an impressive facility but commercially I can't see it succeeding.
The venue won't have the name or history to compete with the likes of Silverstone, Donington or Brands for the international series that only visit this country once a season so it'll be left with mostly national series only and there are very few of those that draw any kind of sizeable crowd (BTCC, BSB and British GT/F4 are the only 3 I can think of off hand)
The need to recoup the huge investment required to build it will lead to it having to charge similar usage fees to the three 'premium' UK circuits mentioned above so your typical low budget clubman series will be put off going there.
I can't see the location helping either, motorsport businesses would rather locate themselves in the tried and trusted motorsport region centered around Silverstone rather than risk isolating themselves.
Eventually all you'll end up with is a very nice trackday venue for those in Wales/The West to use. You only need to look at the car parks full of pallets of compost and the barely used grandstands of Rockingham to see that the demand isn't there to match the ambition of an enterprise like this.
As for their estimates on job creation, I can't imagine the number of full time jobs created supported by a race circuit is even into triple figures let alone the 4000-6000 they are quoting