One thing I have to commend Apple for is how quickly and smoothly this phone detects and connects to networks. Maybe the Droid was just a special piece of shit, but it would literally take 10-15 minutes to realize it was no longer within range of my home Wi-Fi and connect to 3G. If I ever went underground or in an elevator, or otherwise lost my 3G connection, it would take up to 10 minutes to reconnect to the network.
With the 4S, it damn near instantly connects to any available network. It's pretty cool to be able to step out of an elevator and instantly have network access.
I'm sure this isn't something unique to the iPhone, but I'm still very impressed coming from the Droid.