Sorry to give the opposite view but I have owned two GS lexus's Or is that Lexi!
One was a 01 GS 300SE bought with 2K on the clock and the other was a brand new GS430 sport.
The first one went back to Lexus for 6 months as they couldn't cure the vibration through the steering at motorway speeds. Check out the USA forums as they sell more cars there. The only shifted a few hundred of these in the UK so not a good number to obtain any useful feedback.
My Car was featured in AutoExpress three times!!!
Eventually they agreed to do me a deal on a new one after I had run up 20K in their loaner an LX300 very nice motor and gave me no trouble for 6 months!
This was arrange by the then MD of Lexus UK in a personal phone call to me. So in fairness they did do their best.
I then opted for a new GS430 thinking I had just had a bad one, withing 15 K miles the paint had peeled off the front and the wheel bearings went on the front, and the vibration was starting to be noticeable again!
Cost me a small fortune to swap it for something else, so wasn't the happy Lexus experience everyone else talks about. Dealers gave up on both cars and I ended up dealing direct with Lexus technical department.
The GS was a great car to drive if only they had sorted it, really comfortable quiet car which felt very well built, and great engines, apart from the issues my two developed which were at the time well documented in the states.
Best to check the vibration on a smooth straight road around 65-75mph you can normally feel it through your feet
Not driven the latest one, although reports have been good.