While it is true that the GS is has a lot of minor issues, once its fix, it is a near perfect car mechanically. I have own a few Japanese and German high end cars and none of them come close to being perfect. I must agree, the rattles in the GS is very disappointing, Lexus know of the problem since 06 and still to this date have not install the fix from the factory. I guess they are taking the same approach with the rest of the Lexus lineup, they all have issues that Lexus decided to fix it at the dealership instead of from the factory. Thats why the initial quality for Lexus have drop, its all about cost cutting, its cheaper to fix at the dealer than to apply changes at the production line.
When you say lumpy center armrest, do you mean the leather is not as smooth as you like. I have notice that too, the leather on the armrest is not the highest quality. I have tried leather canditioner to no avail.
I never had a problem with the B-pillar or the finish on plastic drivers sill.