The Touch HD display is not better than the Touch Diamond display in direct sunlight. Unfortunately it doesn't come close to the superb direct sunlight performance of the iPhone.
I also own the Sedna and although this device is perfectly usable in direct sunlight, even with the display brightness set to 0, the colors are dull and also much worse than on the iPhone under the same lighting conditions.
I can't hide the feeling that HTC just wants to earn easy money, look at the video performance of the Qualcomm chipset, it should have improved from the TyTN II outrage but nothing has happened yet.
HTC wants to build an iPhone killer? I'm pretty sure they can do it. Unfortunately they would need to charge much more for such a unit or at least lower their profit margin. Apparently they don't need to do that...yet.