That was not the case when I had the test drive, IS250 was not quick to kick down but still a lot faster response than IS300h, but I agree that Lexus setup the gearbox for smoothness rather than performance.
Anyway this is the review extracted from auto express" The 300h is smooth and refined at very low city speeds and on the motorway, but attempt to extract any performance and the whining CVT gearbox, lazy throttle response and sluggish acceleration (despite an output of 220bhp) spoil the fun."