Nonfiction on the iPad

I asked this once a while back, but now that the iPad has been out for a while I want to ask again: how good is it for reading nonfiction books? Specifically, I have two questions for iPad users who read a fair amount of nonfiction:

• How good is the selection of nonfiction? (Obviously this will vary from person to person depending on what kind of nonfiction they read.)
• How well is nonfiction rendered? That is, is the layout of tables, charts, images and so forth similar to a paper book?

I’ve read a ton of commentary about the iPad, but oddly little about how good it is as a book reader. But in my case, that would be its primary function, with all its computerish functions secondary. So what’s the verdict, nonfiction fans?