Despite what others are saying here, you are not alone. Everytime I drive my parents' RX330 I get a little dizzy, then I noticed directly in the center of my line of sight, just below the top tinted area of the front windshield, was an optical distortion about 1 inch high and several inches wide, kind of like a funny circus mirror. Things like stoplights etc, that pass through this section appear to shrink a little. It is very disturbing.
I found this thread by googling, and personally, I don't think it should be limited to the Lexus IS250s/350s. I may be a newbie here at lexusownersclub, but I am active in other vehicle sites, acuramdx.org, acura-tsx and siennaclub.org, which is where you'll find others with issues with Toyota windshields: http://www.siennaclub.org/forum/index.php?showtopic=7135. As we are waiting for the 2007 Sienna's with 261 hp, I am very concerned about Toyota windshields. It is something I will definitely be looking for during the test drive, no use in buying a new car if it makes me nauseous.
I bought a 2008 RX350 in December 2007. I am on the third windshield because of the distortion. I still have it in the current windshield but Lexus is refusing to repair and suggesting I pursue arbitration. I have previously owned an RX 300. It was a perfect car and I did not have one issue. I am really devasted by this. I can't believe that this is acceptable to Lexus or that this is how I am being treated. What have they done to these windshields?
I bought a 2008 RX 350 in March 2008 and I am on my second windshield because of distortion. The second one is worse than the first and I am trying to get action on fixing it again. I have never owned a Lexus and I am extremely disappointed by the lack of quality.