My 4S arrived on Friday and I've been pleased with it so far.
The Siri feature goes a long way towards replacing the "Just Type..." and button shortcut features, with a few caveats so far: 1. Siri can't launch applications 2. it's weird to use it in a quiet office situation.
For the shortcuts, on my Pre, I had a bunch of shortcuts for frequent calls. E.g. I had "Q" call my wife's cell, "W" call her work, "D" for my dad, and several other ones. While I could fiddle with the Phone app and put those things in Favorites, I don't feel a need to do that anymore with Siri. I can say "Call wife's cell" or "Call my father" and Siri will either prompt me for more detail ("Mobile or home?") or just go ahead and make the call. I hope they have (or add) public API's so that other applications can expand on the existing functionality.
Media syncing has been vastly better for me. I don't mind iTunes for the most part, and wired sync has worked fine. I use Aperture for my photos and while there does exist a third-party solution, the native iTunes/iPhone integration works much better. The WiFi sync is quite nice too.
Most of my Cloud data has transferred over without much effort, though my Calendar subscriptions still haven't arrived completely. Contacts and email were effortless (I use Google contacts and my work Exchange for those, though I do miss Facebook slightly, just for pictures).
Notifications under iOS 5 are greatly improved and customizable. I appreciate the fact that I don't have a section of my screen taken up when I have notifications to dismiss and the Notification Center is
I do miss gestures slightly, but it's not a big deal. "multi-tasking" hasn't been much of an issue and the quick-switcher works fine.
The thing that I miss most is the Touchstone. It's so much easier to deal with than a cable. I really wish that Apple had this feature. I'm aware of the PowerMat with sled case option, but it's just an inelegant solution to the problem. For my Pre, I have 3 Touchstones: one next to my bed, one on my desk, and one in my car. No fiddling, no mess, my device went from pocket to charging on the touchstone with no effort. In my car, I even had it mounted on the dash so that I could easily do navigation, music, etc. I also miss Exhibition to a smaller extent, but I only used that for eWeather and News.
I haven't had a crash yet and everything feels very fast. I have only noticed a slowdown once, but only in one app as it was trying to load all of my Google contacts (>1000, I think).
I preferred the feel of the "pebble" against my hand/face, but with one of the bumper cases the iPhone is good enough. The size of the phone hasn't been an impediment, I like the size of the Pre, but the iPhone is much better for me than the ever-growing Android phones. I wish they had a number row on the keyboard instead of having to switch back and forth all the time. I basically never needed to use the Sym key on my Pre, but typing my cryptic passwords on the iPhone is a minor chore when I have to switch back and forth to multiple views. The fact that the keyboard changes depending on context is a blessing and a curse. I really wish I had access to the @ and . keys all the time.
Overall, I have been quite pleased with the hardware and software. The huge range of things in the App catalog can be overwhelming, and it can be hard to find a good choice among the options.
More later, perhaps. I've rambled enough for now.