I didn't know about the jerky transmission when I bought my 2005 ES 330. The demonstrator didn't jerk. If it did, I wouldn't have bought it. The reason people pay for a Lexus is too avoid problems and not to get a jerky transmission. I was going to have the dealer install the software update to improve the transmission, but they told me that, once installed, they can't undo it, and it doesn't always make things better. In the meantime, I put another couple thousand miles on my car and the tranmission (it's supposed to learn and adjust to your driving) now seems somewhat better. I'm not sure whether the transmission has gotten used to me or I have become used to it. In any event, I now have 5000 miles on it and it is smoother with only an occasional jerk. The service rep at the dealer told me that the ES 330 loaners are driven by many different people, with many different driving habit, and that seens to improve the jerky transmission problem. Maybe that "learning" transmission learns quicker with a variety of drivers. So husbands and wifes should switch off driving it.
If you're planning to buy one of these cars, I would recommend you test drive the exact one you may buy first to make sure there isn't any jerk in the transmission. It usually occurs when you are slowing down and then step down on the gas before stopping (like when the light turns green before you come to a complete stop). It also can affect the downshifting.
Aside from the transmission, the ES 330 is a good car, but when you consider the cost to buy it and the pricey upkeep just because it has the name "Lexus," you shouldn't get any problems at all. If I had it to do over again, I would probably buy an Avalon and get a little more room. Al