Monkeyboy51,
From this and other posts I've seen, you really have a thing against the 1.2vti.
The gearbox and clutch may not be the best, but "nasty", no, definitely not.
Flat spot, never noticed one, this is a 3cyl 1.2, put your foot down it's not going to fly.
MPG, I get about 50mpg, on my motorway commute to and from work, going with the flow in the fast lane (and I don't hang around). It would be better on A roads, as it does start to drink petrol at "higher" speeds.
I think your problem must be with the way you drive it, it's not meant to be a boy racer, its for getting you from A to B comfortably and efficiently, which it does admirably.