From Walt Mossberg’s review:
[I] had no trouble typing accurately and quickly on the iPad’s wide on-screen keyboard. In fact, I found the iPad virtual keyboard more comfortable and accurate to use than the cramped keyboards and touchpads on many netbooks
From David Pogue’s review:
When the iPad is upright, typing on the on-screen keyboard is a horrible experience; when the iPad is turned 90 degrees, the keyboard is just barely usable (because it’s bigger).
Obviously there are going to be different opinions, but the chasm between the above two is huge. Pogue says it’s horrible or barely usable, Mossberg says it’s better than many netbooks. In his non-tech review, overall Pogue likes the device; it’s hard to imagine he could do so if the keyboard is really as bad as he says it is. But then why the hyperbole?
I love the software keyboard on the iPhone, and am very comfortable with using it. The vaunted physical keyboard on my new Blackberry Bold is crap compared to it. I expect the iPad’s to be great. Of course I won’t know for sure until I try it, but it’s not like the experience of iPhone OS is a new thing to me, I’ve been using it nearly three years.
[UPDATE:] On live.twit.tv Andy Ihnatko unveiled the iPad, and he said the keyboard was “really, really good”. He thought it would be merely good enough for typing notes, URLs, etc, but it’s much better.