I have the White 32GB 4S and coming from previous phones 3G White 16GB, then 3GS White 32GB, then Black iPhone 4 32GB, I think the upgrade is worth it, however the only one thing that seems to bother me is the way the screen is glued to the fron glass, I can see a dark shadow around the screen and the white phone does not look like the white iPhone 4S or 4 for that matter on Apple.com.
I really do not use Siri
I love the Speed increase, Web browsing and 3G Enhanced access, it is smooth also, and the main reason I went to this one was the camera, it is absolutely hands down way way better than my 4 which seemed like marginal at best when I was not getting blue spots across my photos.