The Nexus S 4G is the spitting image of the Nexus S - aka the Google Phone - save for two differences: It's on Sprint, and it's blessed with 4G WiMax. But it doesn't ravage your battery life. Say whaaaa?
Pluses Unlike other 4G Android phones, the Nexus S 4G has a nifty trick up its sleeve: When you're not actively using WiMax, the radio idles, conserving your battery life. When you call upon it to deliver super-speedy 4G internet, it kicks back on in a matter of seconds. Battery life is a shorter when 4G's running (obviously), but it's not noticeably different. With a couple of tweaks to auto-updates and screen brightness, I was able to go 1-2 days between charges (under moderate use).
And because it's on Sprint, it has full Google Voice integration, meaning the phone seamlessly merges your carrier stuff with your Google Voice stuff, sans app. Use your phone like normal, but everything - from call logs, to text messages to voicemails - is logged through your Google account, for posterity. This is fantastic.
Minuses It feels every bit as cheaply constructed as the original Nexus S. The battery also takes forever and a day to fully charge (meaning 4-6 hours). Google Talk video chat works over 4G, but even talking to someone who was on Wi-Fi, it was choppy, stuttery and dragged. There's also a weird glitch that seems to affect data transfer across the OS: If your signal temporarily kicks out while you're trying to transmit data through an app, the app gets stuck, forever trying (and failing) to send a tweet or IM.