When the Zune HD launched, there was an interesting blog post on the Apple-Insider site. They wanted to 'smash' five myths on the Zune HD, and one of the Myths is about the OLED display. They claim that OLEDs consumer more power than LCDs, are less bright, do not last long and are bad in direct sunlight. Barry Young from the OLED Association has responsed in his own blog post - basically saying that OLEDs look better, have even longer lifetime than most LCDs and consume less power.
Barry also says that when Steve Jobs first saw an OLED display, he said that's the best looking display he had ever seen. We're all waiting for Apple's first OLED product...
The only truth in the Apple-Insider article is probably about the sunlight visibility. We have discussed this issue before, and Zune HD users are indeed complaining.
The Zune HD has actually got great reviews, and it was sold-out within days of its launch. Some consider it as the first real competitor for the iPod touch, and most people love the OLED display. The Zune HD costs 290$ for the 32Gb version, and 219$ for the 16Gb.