Even more than when he's performing on stage, Steven P. Jobs's passion for personal computing comes through when he talks about the years he spent cajoling his designers to build what he presented today as the world's "thinnest" computer.

Along with David Pogue, the Times technology columnist, I spent a half-hour with Mr. Jobs after he introduced the MacBook Air this morning at the Macworld Expo. And as is frequently the case with Apple products, he pronounced the three-pound aluminum-clad portable to be one of the best things his company has ever designed.

"I'm going to be the first one in line to buy one of these," he said. "I've been lusting after this."

The company's design team went through roughly 100 design prototypes to find the right form, he said. Both he and his lead designer, Jonathan Ive, were not certain that they would be able to fit the computer into the package that they came up with.

Earlier, during his keynote presentation, Mr. Jobs went to great lengths to extol the engineering effort that had gone into reducing the size of the basic computer to fit inside the computer, which tapers in thickness from .76 inch down to .16 inch. The circuit board is about the length of a pencil, he said, and he brought Intel's chief executive, Paul S. Otellini, on stage to congratulate him for his company's work in significantly shrinking the packaging of the Core 2 Duo microprocessor that the MacBook Air is based on.

Still, the machine is a reversal of field for Mr. Jobs, who in the past has insisted that less-than-full-featured laptops are undesirable. Today Mr. Jobs was unwilling to compare the MacBook Air to the original Dynabook vision, a portable prototype idea first conceived of by the computer scientist Alan Kay. He would go no further than asserting that this is the most elegant computer the company has created, right down to the four rubber footpads that support it.

Some of the competitors' machines are so flimsy, he said, they require a fifth or even sixth pad to keep from sagging.

Mr. Jobs can be like that when he assesses the competition.

Today he had a wide range of observations on the industry, including the Amazon Kindle book reader, which he said would go nowhere largely because Americans have stopped reading.

"It doesn't matter how good or bad the product is, the fact is that people don't read anymore," he said. "Forty percent of the people in the U.S. read one book or less last year. The whole conception is flawed at the top because people don't read anymore."

He was equally skeptical about Google's decision to develop smartphone software. Google bought a small start-up called Android several years ago, and a team of developers is now putting the finishing touches on an open-source smartphone operating system designed to rival both the iPhone and Microsoft's Windows Mobile software.

"Having created a phone its a lot harder than it looks," he said. "We'll see how good their software is and we'll see how consumers like it and how quickly it is adopted." In seeking not to get locked out of the mobile phone world, "I actually think Google has achieved their goal without Android, and I now think Android hurts them more than it helps them. It's just going to divide them and people who want to be their partners."

One of the remarkable qualities that Mr. Jobs has is his ability to continue looking forward and not focus on the past. For its Apple TV set-top box, "Take Two" is a great example of the computer impresario's ability to recast an anemic first effort with great fanfare. Apple not only cut the price of the box from $299 to $229, it entirely revamped the user interface to a simple text display that is stark even by Mr. Jobs's Spartan aesthetic.

The message now is that when it comes to television, the solution is "all about movies." That can be seen in the movie icons that now fill the screen of the Apple TV display, allowing viewers to choose and rent titles to download.

The model will not extend to cable television, he insisted. "We're not going to go there with the cable cards," he said, referring to the relatively open cable industry connectors that are gradually allowing companies like TiVo to replace the standard set-top box. "That whole industry, their go-to-market strategy is pretty loopy, and it's fractured," he said. "Our model is like DVD."

Mr. Jobs saved his greatest compliment today for his former archrival Bill Gates, who has now largely retired will retire from Microsoft this summer.

"Bill's retiring from Microsoft is a big deal," he said. "It's a significant event, and I think he should be honored for the contributions he's made."

By John Markoff