I think the BlackBerry Torch 9800 may be the best BlackBerry smartphone yet. I've used the Bold, the Storm, and many other BlackBerry devices. The Torch combines the best of both worlds: a touch screen with a hardware QWERTY keyboard. I'm not sure why they chose the vertical slider orientation as opposed to the horizontal slider. Maybe they felt that the majority of their users would prefer the vertical orientation.
Personally, I'm a big fan of the vertical slider. Why? You can type you're holding the device in one hand. All you need is a single thumb that can move across that QWERTY keyboard. You can try that on a horizontal slider, but you'll have some difficulty balancing that phone if you're only using one hand.
If you're a former Palm Treo user, the BlackBerry Torch 9800 could remind you of the old Treo (except the Treo wasn't a slider).
It's too bad that the Torch is only available on AT&T.