I have recently bought mine and also bought the warranty (it will be 10 in November).
The rear dampers were leaking when I bought it, and the car needed a warranty inspection at the dealer first, before the warranty was approved.
They'll spot the shocks and not cover them - I asked another dealer (not the one it went to).
True enough, once I had the shocks done, the warranty sailed through (and I had the 100+ service done at the same time) - not a cheap day!
But - 10 year old car, 2 years total peace of mind, and it comes with Lexus Assistance (which is worth £270 over the two years). No brainer.
Brian.