I went to a distant Best Buy to see what the iPad is like today. I like it (I was mostly looking at it as an ebook reader). The books on iBooks look great (Winnie-the-Pooh with color pictures!). They didn't have the Kindle app loaded, so I didn't get to check that out, but I hear it's really nice. It is a trifle heavy, even compared to the DX, and I think one would generally want to read it lying down, or with the iPad on a tabletop.
If I buy one, it would be the cheapest model, with wi-fi, and I'd just buy my books at home. I'm not getting yet another device with a monthly charge. But I really am tempted to buy the cheapest model (when it's available; right now they don't have any in stock). I'll let you know if I buy one!