It's been over 2 weeks since I swapped out my iPhone4 for the Nexus S running Android
T-Mobile does bring some measure of joy to the experience, as it delivers connectivity in the Hollywood Hills and surrounding area that is superior to AT&T and Verizon, the only two choices available for the iPhone. It even works all up and down Sunset, as the No Agenda Stream usually would crap out near the Chateau Marmont, as the iPhone would switch to 2.5G, not enough bits to handle the 128kb stream.
As for the phone itself. I kept it pretty much stock, as it comes out of the box from Google. I disabled auto-synch of all google services, don't need them anyway. That switch makes all the difference with battery life. I get a full day on a single charge using primarily wifi. I've set the phone so the 3G isn't activated unless there isn't a wifi signal, yet I deactivated the wifi from switching off when the phone is 'locked', since that hinders reception of google voice text messages. The google voice service *does* run data synchs in the backround by my choice.
I'm using K-9 mail as my imap client, and it only grabs headers periodically and displays alerts in the top menu bar when a new message has arrived, yet doesn't suck in the content until the app is activated and the inbox accessed. Smart.
The phone feels nice in my hands, looks stylish enough for this 46 year old, and has proven reliable in every aspect of use.
What I like best of Android over iOS is that I can clear out all alerts in the top menu bar with one button. My favourite difference is how a double tap on a paragraph in a web page not only zooms in like the iPhone, but it actually re-formats that page for small device viewing.
I also like the 'breadcrumbs' path when backing up from a screen. Using the back button will cycle through all the screens you saw, regardless of application. This is a great way to utilize multi-tasking.