I'm due an upgrade, and dithering. The desireHD has a nice big screen, good point, but from reviews/forum posts has a crap battery and is a bit buggy, it supports flash, good, but I have an android phone atm and I'm a bit bored of it tbh.
I have never had an iphone so ios will be new to me, which is good, also it has a nice screen/camera, better apps and higher resale value.
I quite fancy the iphone but the small screen is bugging me, when browsing will I constantly be resizing/zooming in? I'm not that arsed about flash really, I don't get much time off for good behaviour 
. So use the phone mostly in the house.