Our '04 LS430 is a great car. Powertrain is well designed and will last 300,000 miles + if cared for. I would want to see service records before purchase. The timing belt 100,000 service is costly. Michelin tires are great if installed. The optional GPS electronics package seem marginal, as is optional ride control. I would stay away from a car so equipped.
We bought the car 8 years ago with 100,000 miles on it, and knew the original owner. Car was always serviced at the Lexus dealer, a GREAT find on a used LS.
Things that went south on our LS in 8 years: tires, brakes, O2 sensors, passenger door lock, headlight movement, steering wheel movement, back window screen, hood and trunk struts, driver seat leather.