Check out this in depth review of the Samsung Focus S Windows Phone. The Focus S runs Mango and is a nice upgrade over the Focus. PocketNow has done a fantastic job of giving you a detailed hands so you can determine if the Focus S is for you.
The AT&T Samsung Focus S is quite an upgrade over last year's Windows Phones in the specs department. Its dimensions are 66.8 x 126 x 8.38mm, and weighs only 110g. That's very thin and light! Its 32-bit Qualcomm Snapdragon MSM8255T processor runs at 1400MHz. It's got around 15GB ROM storage as well and an amazing 4.3" 480x800 Super AMOLED Plus display. For GSM and 3G band support, it has GSM850, GSM900, GSM1800, GSM1900, UMTS850, UMTS1900, and UMTS2100. It's also got a new eight-megapixel camera with flash and focus illuminator, as well as a secondary front-facing camera.