I got the Desire HD + Reliance 3g connection from a friend to use for 4 hrs & here is my observation.
Most apps need 3g connection so I faced the signal problem in my room I had to move to the terrace to get 3g working.
The handset is pretty heavy to hold in 1 hand though its only 170gms, it will soon cause you RSI (Repetitive strain injury) with 2 hands its quite comfortable.
The handset does not come with any cover & its quite easily scratch able from the back.
using your finger leaves finger marks on the screen & then every now & then you will have to wipe the screen.
The glossy screen is not usable in outdoors, it reflects too much of your own image thus not usable for other feature except that you can dial a number for sure.
The image quality of images/video & flash presentation is extremely good but in indoors only,
outdoor the screen looses its worth even though its HD.
The installed apps are feature packed & you can download more for your use.
Web browsing using flash content was quite comfortable without any hangups.
image zoom works well too.
If I ever buy this i surely need some kind of dock station to hold the handset, a screen protection cover & a blue tooth ear plug so I can talk hands free.
In using for 4 hrs i felt i will have to do a lot to adapt to using this smartphone.
Will try a desire Z soon.