I've never had a situation where the engine is 'screaming' as frequently highlighted by some magazine journos.
Their reports are like they are deliberately trying to downplay what is a very good car and therefore serious competition to their advertisers.
The only situation where I've felt the Jazz Mk4 could be more refined is with ACC. If for example, after setting a speed of 70 mph the car decelerates (because of another car coming into your lane) then, once road is clear and the Jazz is able to return to 70, it does so by going - what sounds like - full throttle.
So it's an unpleasant change, primarily because the car is such a refined motorway cruiser in all other respects. Likely, better throttle mapping / software changes could dial back on the rate that ACC comes back up to the set speed (which would be ideal). But certainly if ACC is off, then I've had no issues like that.
A "trick" to make acceleration even more seamless is to use ECO mode. Yes, it dulls the power a but, bit going between full EV mode to hybrid mode is smoother once you reach a certain speed.
I agree, definitely have another test drive. But in videos / articles where "screaming" is mentioned, it's only because - against a backdrop of the Jazz being VERY quiet 90% of the time - the 10% (with the ACC example I gave above) comes as a bit of a shock initially.
And those comments apply to A-road / motorway driving speeds, not to driving in town (where things are always pretty hushed).
I do my love my Crosstar and even the above 10% does not detract from the fact that it's an extremely clever and well-engineered car. Its competitors seem dull in comparison, especially when it comes to practicality!