I had my trusty HTC Magic for over 2 years; it was getting a bit long in the tooth. Battery life wasn't too good, it was slow etc. So on Monday I took delivery of a Nexus S.
It's really an incremental upgrade, bigger screen, better battery life, faster. The OS is the same, so the things I used to do on the old phone are done the same way in the new one. The hardware though has additional features such as NFC, which I've yet to get my head around.
In choosing the phone, I wanted it to be as open as possible, so I wanted to avoid the proprietary UI add-ons such as Sense which HTC uses. Also I wanted the phone to be designed for people to have root access to it, without having to jailbreak it. The Nexus S fits the bill.