It's good, but it's considerably too small & too thin
I've had one since October & overall I like it.
The battery life is appalling - it lasts about 6h in normal use, which I do not regard as heavy. It's the first charge-twice-a-day phone I've owned; I now constantly carry a charged spare battery & a USB charging cable.
It really would benefit from simple cursor & select keys & make/end call buttons - both for ease, precision & for use with gloves, for instance. You lose the onscreen cursor keys with Swype or any other enhanced keyboard; even with these tools, text entry & editing is infuriating, slow & painful. Entering more than a short paragraph makes me shout at the device in rage.
Those whinging about its size are munchkins, hobbits or something. The Desire HD is *too small*, if anything! A phone should reach from ear to mouth; this thing is a good inch+ shorter than its predecessor, a Nokia E90, & HTC's battery is just laughably tiny.
It would benefit a lot from being 2-3cm longer with some of the extra space used for just a few physical buttons. It also really needs to be twice as thick, with a big slab of detachable battery on the back - it needs something like 3500mAh to be usable *as a smartphone* all day. By which I mean calls, email, social networks, GPS, some music playback, occasional Web use, etc. Even with spare batteries I daren't listen to music or run the IM client on mine - it would die in a few hours.
Of course, then the little tiny people with their little tiny child hands & tiny miniature pockets would whine - but sod them, they have an abundance of microscopic kiddie-sized hairdressers' phones to play with. Let 'em whinge.
Better still, a slide-out keyboard on a phone with a screen this big - or bigger. An Acer Liquid Metal with a half-decent keyboard and a 3500-4000mAh battery would be ideal.
But no, oompaloompas rule the mobile-phone world these days, so even we proper man-sized actual *adults* are cursed with phones designed for infant People Of Restricted Growth.
For comparison, my old HTC Universal, with a 3rd party extended battery of ±3800mAh, could last for about 2½ days on a charge. Go to work Friday morning, go away for the weekend & it was still running when you got back to the office on Monday morning & could charge it. *That* is a credible battery life. The Desire HD's is a joke. Yes, it was 1½" thick & weighed about 400g, but it was totally worth it.