It has got to be the touchscreen/trackpad combo. Having the ability to navigate a touch screen with the trackpad is a really great feature.. it speeds up some tasks and the ability to just use the touch screen when its convenient is great.. i love the combo.
I was really surprised because i had read a comment in the past about it being overkill, but it's one of my favourite features of this device.
I find myself using the trackpad more often than the touchscreen. In fact, I probably wouldn't even mind if the Torch wasn't a touchscreen phone at all, if only I didn't like SureType so much.
Another underrated, or under-appreciated feature is the locking of the accelerometer when the keyboard is slid open. That was actually one of the main reasons why I switched from my Storm2. I wish I could open up the phone and disconnect the accelerometer completely, but sliding out the keyboard is at least far more convenient than locking each individual application through the menu.
Been using the Torch now for about 2 weeks and have used the physical keyboard maybe 5 times at most. Most times I forget that it's even there. But then I upgraded from the Storm1. Missing the sure press though.