A few 6ESs have developed problems with door lock actuators.

Also many '13 and '14 models have problems with ventilated seats loosing efficiency.

Other than that surprisingly reliable car - even by Lexus standards.

So which one is it?

I had a 2004 ES 330 for about 9 years. Great car, was never in the shop for anything other than routine maintenance. In 2015 I decided to upgrade to a 2013 ES 350. I always buy mine CPO with under 30k miles. Went to the dealership and they had just gotten a 2009 GS 350 AWD and not sure what happened but came home with it.
The 3rd Gen GS is a great car but I regret not getting the ES so was thinking of upgrading again, looking at the 2016's as that was the year they switched assembly to US, so I don't have the exact numbers but a good number of them are Japan assembled and then the rest of them are US and when searching for a 2016, the first thing I look for is the VIN as I believe you cannot match the precision of a Japanese assembled car.
So just curious, any positive/negative feedback as to any degrade in quality in the US assembled ES 350's? I looked in the 7th Gen forum and a fair amount of issues so wondering if its just me or there really is a difference in quality.

I had a 2013 Generation 6 ES built in Japan for 3 1/2 years. I now have had a 2017 US-built ES for the last 2+ years. I'm quite particular about fits and finishes. The Japan-built 2013 ES was generally good with regard to fits and finishes, but it was far from perfect. The alignment of exterior panels on the car was close, but it was not quite perfect. Similarly, the alignment of a couple of interior trim panels was not great. With the 2017 ES, the fit of both exterior panels and interior panels is about as close to perfect as possible.

I know that my sample size of 1 US-built Generation 6 ES and one Japan-built Generation 6 ES is small, but, after my experience with US-built car, I would have no hesitation with regard to buying a US-built ES. Further, after regularly reading posts on the Generation 6 ES CL board, there has been no noticeable difference in reports of problems on 2016-2018 US-built ES and 2013-2015 Japan-built ES.

At one time I had a Toyota Avalon that I believe was built in Kentucky.. My ES was built in Japan. I can honestly say I didn't notice any real issues with fit and finish on either car. In fact I remember thinking that the leather work on the american made avalon was quite good.

My '13 is from Japan and it had the sunroof rattle problem that was a *itch to fix (car was left at the dealers for over a month). I wonder if that problem was limited to cars from Japan or if that design issue was also in US built cars?
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My karma just ran over your dogma
Current Hers: '13 Lexus ES350
Current Mine: '15 Jaguar XF (its aubergine)

All 2013's were built in Japan.

Pab12... My Avalon had a sunroof rattle issue, but it only rattled in cooler temperatures. I noticed that when it got down to 45 degrees or colder the darn thing would rattle... It actually sounded like it was coming from the glove box area, but I did some research and people were describing the exact same thing I was having with relationship to cooler temps. It was explained as being due to some expansion and contraction in a metal part in the sunroof mechanism. At the time my car was out of warranty and the dealer wanted to send it to a trim shop where they would tear it down and find the problem. I did not get it fixed because as soon as the heater warmed the interior of the car, the rattle stopped.. plus I was already looking at Lexus so I didn't bother with a repair.

>It was explained as being due to some expansion and contraction in a metal part i
I don't think that was the same thing. My repair involved some problem with the tracks that the sunroof uses to move and/or cables used to move the runroof. It was a common problem in different Lexus (a friend with a ~2010 LS first explained it to me, it was present in that series of cars, too.) The entire sunroof had to be replaced (under warranty, whew..).
The noise I heard "seemed" to come from behind me, so I spent a lot of time trying to locate loose pieces of rear seat trim, rattles from the trunk, etc. It was only when I talked with the fellow with the LS that I realized that the rattle was coming from above and behind my left shoulder. Once he clued me as to where to listen I could definitely confirm the source of the noise.
It was a very expensive job (~$2000 + over a month of a loaner car). The runroof tracking flaw was corrected in 2016 models, I believe.
The dealer had no problem when I brought the car in. I just mentioned hearing the noise and identified where I thought it was coming from and they immediately took the car in. At the time (December 2017) they had at least two 2014s in for the same repair. That was probably why the repair took as long as it did. The supply of replacement sunroofs was low and they had to wait for one to arrive from Japan in order to fix my car. I suspect that had they known of the backlog they would not have given me a loaner and taken my car when they did.
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My karma just ran over your dogma
Current Hers: '13 Lexus ES350
Current Mine: '15 Jaguar XF (its aubergine)

ES300h with LKA and radar cruise, does it steer when you get out of the line?
Does it have all speed radar cruise?

With the Generation 6 ES, the lane keep assist does just that. It assists. When the system detects that you are wandering out of your lane, it gently nudges you back toward your lane, but it does not actively steer or try to keep you in the center of your lane.

No, the radar cruise control on the ES is not an all-speed cruise control.

For what they are, though, both the lane keep assist and the radar cruise (with auto braking) do work very well.