Sorry to hear that you are disappointed. My very small experience of the GDI engine did not reveal such a flat spot. 500 miles is really very little and I noted that my wife's Polo became much more lively once it had about 5,000 km on the clock. My own pre GDI (now with throttle bodies) did not have a particular flat spot but I did have a sports exhaust from new.
Regarding instruments misting up I have just realised that I have not had this since I had the instrument faces changed to magnolia colour and fitted LEDs for the instrument lighting. Previously it was common in cold weather. To me this really is an issue that should have been resolved year ago: modern motorcycle instruments do not suffer from this problem so why should sports car instruments.