I had a touch screen (Nokia 5230) for ages and ages, and never quite got used to it. I got up to a decent speed with the Swype on screen keyboard software, but it still wasn't the same as a real keypad and it took a lot of concentration to type the right words! Having to look at the screen constantly was irritating.
Now, I'm using a cheap Android, an Alcatel OT-980. It has an awful unresponsive touch screen, but it also has a slide-out QWERTY keypad and despite it being a bit of a cheapie no-make cell phone, it's possibly the best phone I've had for my needs, which are mainly messaging. I can tap out quite long messages really quickly.
It's horses for courses - lots of people love their touchscreen iPhones and Desires, but for me personally, a real keypad can't be beaten.