I purchased the IS as a more reasonable replacement to my '02 RX 330. While there was certainly a period of adjustment getting accustomed to a smaller vehicle, it is a decision I do not regret at all. It is a fun, sure-footed vehicle that gets good mileage when you can resist the urge to test it's limits... but it is so accommodating that you find yourself driving faster than usual. The interior lacks storage, especially after driving an SUV, but does not lack fit or finish.
Acceleration or mileage (never both at once!). Secure, confident ride.
Incorporate the memory seats and expand drivers area storage.