I'm considering one although I'm really happy with my Cooper S at present........agree with Dark Knight's review as when I test drove the ST in May I didn't think it was as responsive as my S but with the Mountune kit fitted it would be a different animal I suspect.
That said, we do have a beautiful Fiesta 1.0 125bhp Titanium X in frozen white (my wife's car) and that is a real joy to drive; lovely comfortable seats, no road tax, cheap insurance and even though Janet only drives a handful of miles to work and back most of the time with the air-conditioning on, it's still returning nearly 40mpg which will get better (hopefully depending on how much she likes the loud pedal) as the car has only done 500 miles!