I would say my experience with Jazz cars (now on my 4th) over the years has been very good.
I'm not one for speeding much, just set the cruise control to 70, sit back and enjoy the journey, I suppose my longest trip in a day has been up to Scotland, roughly 325 miles and did not suffer any undue affects from the journey.
I can't speak for VW, most of the previous cars has been Rover products , metros, 200 series etc and a Freelander and I can say that the Jazz is equally as comfortable, if not better.
My fuel consumption is usually in the mid 50s on such journeys.
So I would say, go for it, I don't think you will regret it.