The LS 400 is unbelievably comfortable and quiet. Trips of 3 or more hours are a piece of cake. It handles well for a luxury sedan and gets surprisingly good gas mileage for a V8. As others have said, the workmanship is unparalleled. This is far and away the finest automobile I have owned. My wife has an Infiniti that I thought was top shelf until I bought the Lexus LS 400 - there is no comparison.
Reliability and workmanship. The car has required absolutely no maintenance other than regularly scheduled oil changes.
I agree that the accelerator can be a bit tricky. I expected the trunk to be larger for a full-sixed car. My wife's I-30 has a larger trunk than the Lexus.