The iPad can play HD video for an estimated 10 hours. That has nothing to do with the glassy interface, but I would still call it great hardware design.
Absolutely. I don't think many people appreciate just how dedicated Apple is to excellent power management. The iPad is a dramatic example, but Apple has excellent power management across its product lines. Macs have had near-perfect power management for years, whereas PCs still struggle to get it right. This is one area where controlling software and hardware is a huge win.