All devices with SAMOLED screens have great battery life, the Gingerbread UI is black and dark 99% of the time, SAMOLED basically turns off or hibernate the blacks so it saves battery life. That's why TouchWiz on the original Galaxy S series was dark colours. By the way, the plastic build quality is better than the one that the iPhone uses, which breaks instantly if dropped from a foot off the ground. I would much rather have the Samsung plastic bodies then the glossy glass that Apple uses.
Sent from my Xoom