My opinion; I don't like it. The targa (Surrey) concept makes sense for cars that have a lousy (e.g. leaky and drafty) soft top, like our loved LBCs. But the Miata does not suffer from this.
And I agree with the comment that each Miata is less liked than the previous - except for the current. Aesthetically it is "different" (i.e. we may like it or leave it), but it is lighter and smaller than the previous generation. Classic Motorsports compared its dimensions to an MGB. Quite close, actually smaller in some areas.