Before I got the Desire HD I read so many user reviews. I couldn't find one that gave me actual usage and battery life, I'm an It consultant so I do a lot if research on things like this before I spend my hard earned cash.
I have read so many reviews that complain about the battery, thought I would take the risk and get the phone anyway, and have had it for almost a month now with the phone improving every day, feature and battery wise.
In my experience the battery life is good enough in todays world of high powered, feature filled smartphones.
The phone is setup with the screen on 50% brightness as I haven't found the need for it to be any brighter, WiFi and mobile data with auto sync enabled all the time. I have Facebook, weather and news syncing every hour and exchange and hotmail email every 10mins. My normal working week involves a 3 hour train journey each day. During this time I use the phone for a mix of listening to music, watching videos, playing a few games and browsing the web, some of which is done at the same time. During my working day I average around 1 hour of call time, about 45mins sending sms messages and the rest the phone is idle working away on its own with the setup sync schedules. At the end of a 12 hour working day I have on average around 25% of battery life remaining.
Yesterday was the first time I used the mapping feature thinking it would use a lot more battery with the gps, to my surprise I found the pub I was looking for within 5 mins of using the map whilst listening to music and spent the night sending a few sms messages and showing off my phone to friends and got home with over 15% battery left, as I type this review I have just got a notification that my battery is at 5% and I should charge it. The phone has been off charge for 1 day and 2 hours.
To my expectations of smartphones I am impressed with the battery life, possibly because I have read so many bad reviews and wasn't expecting this much battery life.
I have had to plug in my charger as the phone died but with the quick boot function and the Android memory management I have not lost any of this review. The hardware is fantastic, all the way from the inner components to the casing and screen, which might only be an lcd, but can only tell the difference in the blacks and whites if you are looking for it. The camera is great, picture quality is very good for a phone.
Just a footnote I have never owned an iPhone so cannot make any comparisons, my last phone was a Nokia n97 and this beats it hands down. Not knocking the iPhone as it is a brilliant device, a friend has one and his died last night after approximately the same kind of use I make out of my phone, so he had to borrow mine to make a call... in my mind that's a victory for the HTC Desire HD.