Brief: a medium sized high technology, luxury sports car which will have 1 or 2 people in it most of the time. I researched and drove BMW, Audi and Mercedes before settling on Lexus. I was upgrading from a SAAB convertible. To compare the cars, you need to spec up each car equally, which I did. The Lexus is the best value by many thousands of dollars. The car is a powerful, smooth quiet ride if that is what you are looking for. My average speed around Sydney is 38 kph so top end performance is nice to brag about but not a decision maker. Add an extra year's warranty and a world rating of most reliable car and you have some very good reasons for buying an IS250. It exceeds the brief!
Practically, the touch screen for all the essential controls (air con, sound, GPS, telephone, rear camera) is so easy to use. The BMW, Audi and Mercedes have far less user friendly, non touch, user interfaces. The IS250 is a little pocket rocket of technology, I love adaptive cruise control!
Rear legroom is limited but no more or less than its direct competitors. The "key" that you must have on you but don't use because of keyless entry and keyless start is a pain. It sits in my pocket as a lump or I throw it on the passenger seat!