Actually, Alan Kay appears to be a big fan of the iPad concept.

From Janko Roettgers:

I interviewed Kay late last year, and while he didn’t mention the tablet by name, he did share a story about the unveiling of the iPhone, to which Steve Jobs invited him in early 2007:

“When the Mac first came out, Newsweek asked me what I [thought] of it. I said: Well, it’s the first personal computer worth criticizing. So at the end of the presentation, Steve came up to me and said: Is the iPhone worth criticizing? And I said: Make the screen five inches by eight inches, and you’ll rule the world.”

Guess about how big the iPad's screen is?