Pro's
The Desire HD is generally a great phone, its fast, yes by today's standards it doesn't have a dual core, but the 1Ghz single core is perfectly adequate for the OS and games you might like to play on it, plus backed up by the heavy 768MB of RAM, makes it a great at multi-tasking since all your previous apps can stay open without it getting slow.
It is (was) also really easy to gain root access to allow for customization and overclocking, a tool called Visionary+ is used to do one click rooting, (EDIT: An software update for the Desire HD, made the one click rooting impossible, although a roll-back to an older version is possible and then you can root and flash custom ROM'S)
One I obtained root access I found on XDA that the Desire HD is very overlcockable, even up to 2Ghz, I originally had mine at 1.6Ghz, but poor battery life became a pain and now it is comfortable at 1.22Ghz alongside the Android Revolution HD 3.2 that I am currently running. The phone is generally very snappy and the wide range of Sense and Non-Sense ROM's that support this phone is pretty good and it is pretty easily rootable even with the newer firmware.
Con's
The Desire HD's con's are mainly build quality, I feel that HTC's build quality in the main is good, and the phone is very aesthetically pleasing and feels very solid in the hand. Yet mine seems to be falling apart, apart from a small dent in the top where I dropped it, it hasn't sustained any other fall damage, the things I am about to talk about just generally happened in day to day usage.
Volume rocker, well I cant put it any simpler, it fell off, one day it became loose, and I intended to glue it in the centre, where it rocks, but on my way home I must have lost it when putting it in and pulling it out of my pocket,
This makes it very hard to operate the volume controls as you might imagine, but I can still just press the buttons if I stick my finger nail in there.
The next thing that I hate is the fact that the aerial cover, falls off, continuously, it just wont stay on, I had the phone for about a month, and that's when it got loose and just started to slip off the phone whenever I pull it out of my pocket etc, this is the most irritating thing ever, since, imagine this situation. Your phone is ringing in your pocket, you pull it out to answer it and the aerial cover falls off, the phone call dies due to having no signal since the cover fell off. I'm presuming the clips that hold it on are just weak, but I think this shouldn't have been an issue in the first place.
