Interesting. I have the totally opposite experience.

I find Siri to be a pretty cheap gimmick, and I never use it. It was fun for the first few weeks. It's scope outside the US is currently very limiting, and I find I can't speak naturally to it. I somehow feel like I am barking commands at it as there is little point in being human with it.

I am also finding the build quality of the 4S to be somewhat lacking compared to the 4. There is a rattle coming from inside the phone now and it's lost that block of glass feel. I'm not sure if it's a fault or not but it's certainly starting to feel a little hollow to me.

Cheers

Cris