Hi All,
Just thought that I would add my experience: I am a current SL owner, and previously owned a BMW X5.
The points that I would note in favour of the Lexus are:
Extremely good after sales service - I use Lexus of Brighton and I've been very pleased with their approach.
Loads of standard equipment in the Lexus compared to the BMW: I spent over $20k on extra's for the BMW, and I don't consider that any of that was 'fancy' (parking sensors, onboard computer, stereo upgrade, sunroof and alarm)
A very quiet cabin, although this is a double edged sword (see below)
The not-so-positive observations I have are:
Some of the electronics do not work properly: the ones that don't are the rain sensing wipers, remote (keyless) entry and the ventilation controls. I have reported all these to Lexus, with detailed descriptions and in some cases showing the problem (keyless entry) - the car has now been twice returned with the comment that they have been checked and everything found to be operating properly. The rain sensing wipers are particularly annoying as Lexus have eliminated the (manually) adjustable intermittent wipers I've been used too in my cars up until now. Not a problem if the rain sensing worked, but it doesn't: I have to manually control the intermittent wipe, or put it onto a continuous wiper setting... a total PITA when the weather is wet.
The quiet cabin means rattles are easily noticed. So far Lexus have been unable to eliminate a high-frequency buzz from the ash try (I leave it open and the buzz stops), or a sound from the dashboard (like a spring being stretched, which happens about 1 minute after the car is started).
I find the alarms in the car to be incredibly annoying and totally pointless. I've disabled the seat belt alarm, but the car will let you turn it off when in drive or reverse ... and if you do, it goes beserk when you try and get out. I figure that these alarms make sense if had forgotten to put the car in Park and/or not engaged the parking brake before getting out, but they chime away anyway. You have to restart the car and then turn it off again to clear the alarm.
I really like the style, build quality and after sales service of the IS250 and Lexus, but I find that I don't like the car anywhere near as much as the BMW and I would be unlikely to repeat the purchase. Everything in the BMW just worked: no stupid games with rain sensing wipers, no watching what gear the car was in before I turned it off.. and no buzzes and rattles to irritate me as I drove.
To me the value in owning a car is the enjoyment you get from it ... and although some of the problems are minor, they have spoiled the enjoyment of driving it. I don't want to say that others are wrong to tell you how much they enjoy the car - I only wanted to relate my experience :)
Good luck with your choice!
Cheers,
David