If you were in my place and can afford it, yeah, the itch would make say, what the hell, just do it.
In fact my itch is so great I am even tempted to make a collection of HTc Androids. Strangely, I don't have the compulsion on the dual core Samsung, Motorola and LG phones, even with the dual core vs. the HTC single core.
For me, HTC has this grace, beauty, design and elegance that is very hard to match.
So what does the HD offer the Desire doesn't.
First the GPU on this baby is much faster, like nearly double. While computing related tasks seem the same, everything dealing with graphics tend to fly, like games, scrolling, UI transitions, live wallpapers and so on.
Second, it has 768mb of memory. That means RAM is up by 50%, which means better multitasking. That adds to the sense of speed and improves on the multitasking.
Third, the processor is built on a more advanced .45nm process. In layman's terms, the transistors of the chip are much smaller than the chip used on the Desire. That translates to less power being used per transistor and despite the larger screen, the phone may have better battery life over the Desire.
Fourth, the Desire HD has over 1gb of memory reserved for internal phone memory. That means more apps you can install, far more than the Desire. The Desire only has 141mb of internal phone memory. Note, this is not SD. This is the memory where many apps are installed, though some apps can be installed on the SD card.
Fifth, you got a bigger screen. It is quite obvious.
Sixth, the screen is SLCD. While its not as contrasty or color brilliant as on the Desire (assuming the Desire has OLED), the SLCD screen is sharper and easier to read text. The Desire HD makes a better ereader for sure.
Seventh, and not the least, it got the third generation HTC Sense, and its a big leap over the 2nd generation used on the Desire. I can't say much just to keep the post short, but the differences and additions are quite considerable. Among such changes for example, includes a unified email inbox, ala Blackberry. Another is the cool way of using task or app switching via the notification bar.
Overall, when you add it all up, there may also be a strong enough logical reason for an upgrade.
