My daily driver is a '95 LS400, my wife's is a '92 LS400. Bulletproof drive train, the accessories tend to have trouble as they age like any car. But unlike a BMW or Mercedes, we're talking about an alternator getting weak at 240k miles! Both of our cars are very high miles and were very neglected when purchased - hers had a broken timing belt and a salvage title. But upon tearing into the '92, I found that it had the ORIGINAL timing belt and water pump. Further inspection revealed the original plugs, wires, everything. All had a 1992 date code. What BMW would go 200,000 miles with absolutely no maintenance?
They have no sporting pretensions, but the 1995 is fast in a straight line and the 1998-2000 is really fast in a straight line. It will surprise the driver, the passengers, and anyone around you when you punch it. 0-60 in 6.3 seconds is amazing for a car that rides like and has a back seat like a personal limousine. Not earth shattering for today's cars, but you can get a really nice example with around 130k miles for $8000 if you shop around. [edit for clarity: I mean a 2000 model. The 1995 is available for significantly less.]
As far as it being a "copy" of anything - puuhhleeeze. I would hope that the average GRM reader would know better - after all, our favorite car is a "copy" of a British roadster. Except it does everything better than the Brits ever did - just like the Lexus. An LS400 is everything a German car wishes it could be.
The 1995-1997 models do have a finicky starter. But again, this is a problem that occurs once after 150k+ miles. Mine went intermittent at around 170k and I replaced it. That's the only work I have "had" to do on my car in 4 years - and again, that was a car with a ton of miles on it, neglected, bought at the bottom of the value curve. I paid $3500 for it when the wholesale book value was close to $8000.
Sorry to ramble - but I believe the LS400 is an ideal daily driver if you want a luxury car. It doesn't corner that great, and it only gets around 19 city, 25 hwy mpg, but it'll seat four very tall people in supreme comfort and is dead nuts reliable. Turn off the traction control and you can do burnouts 'till your tires pop. (Unfortunately you'll need to do a brake stand as they do NOT come with a limited slip diff.) They're not all that heavy compared to modern cars, at around 3600 pounds curb weight. For a car this size, that's pretty light.
Personally, I prefer the LS400 for looks and speed over the LS430. The LS430 is heavier, has way more features, and is slower. All of them have amazing stereos, for factory units.
Any specific questions? Feel free to ask. I'll stop rambling now. ;-)
Edit: forgot to add: Curtis sees only the problem vehicles. The Aisin 4-speed transmission in the LS400 is bulletproof. Both our cars are on the originals, one at 180k miles, the other at 240k miles. No problems. Volvo used it in the 960 and didn't have any problems, either.