I bet you'll be saying the same thing if he gets on the court and votes most of the time with Souter. Fact is, he's a pig in a poke - and Republican "pig in the poke" nominees have turned out, without exception to be liberals: Souter, Kennedy, O'Connor, Stevens. If Roberts doesn't turn out to be a liberal on the court, he'll be a first "pig in a poke" GOP nominee who doesn't turn out to be a liberal. His helping a radical gay-rights lawsuit hardly inspires optimism that he won't be another Souter.
Devil is in the details; proof is in the pudding. I'd rather rely on a careful reading of his decisions than your "Pig in Poke" assertion.
Have you even bothered to read the french fry decision I referenced earlier?