I am!

My old impreza had fixed rear seats and was useless.

My new IS has already been several tours to IKEA and loaded full with kitchen kabinets for the garage, I've helped a mate buy some tall shelves and I've even transported a new living room door in it! (the door was standard EURO M9x20 about 195x83 cm. It did fit inside the new IS with the seats folded down.

Also manged to fit the extra materials to the door together with the door itself.

So yes, I've used the folding rear seats many times, and are very happy for this function. Only downside is that they do not fold flat down in alignment with the trunk floor.

 

Not able to use mine anymore because my air box blocks everything, maybe when i decide to move the setup where the spare tire is i can use it again

 

I was so disappointed that my 2011 IS250 didn't have them. I just assumed they would since my 1997 Audi had them but found out after I got it that they wouldn't fold. With the '11 250 I had to rent a car to go snowboarding (since I wasn't about to put a rack on and scratch up my roof). Now, with the 3IS, I can save a little money on car rentals. I am soo loving this car.