Great overview of the iPad 2 by Jeff Carlson for TidBITS:
For several people I know, the size and weight of the first-generation iPad is a detriment; it’s just heavy enough that holding it for long periods of time — even propped against a leg; I’m not talking about elevating the iPad for hours — is tiresome.
I didn’t get a good sense of how much the weight differed; it’s only 0.2 pounds, after all. But the thinness is wonderful, and if anything contributes to a sense that the iPad 2 is lighter than it really is. Your brain sees a sliver of glass and aluminum. Not a slab. Not a slate.