I have an 2006 IS250, It has been a very good old car. I have replaced the following during my 7 years of ownership:
Alternator
2 Batteries
Water pump
All the gas struts (boot, bonnet)
Screen film stopped working last year but I changed it
6 coil packs (one on each spark plugs)
Transmission oil
Differential oil
Centre bearing for the drive shaft
Auto wipers sensor
Things that are a bit tatty:
These are the things I have noticed on the car that are deteriorating:
Side plastic cold getting marked
Body coloured rain strips are fading
Black plastic strips on top of chrome strips on the doors are coming off
Interior drivers side is tatty and I have made numerous not very successful repairs to the dash
Things I have heard happen to other cars
Leather trim holed and worn
Overall it's still a good, not perfect. My car parks on the street but for a 17 year old car there is little to complain about it all still works