Apple (AAPL), which recently reported a rare earnings disappointment, has whipped its fan base into a frenzy with the iPad Mini. Demand quickly outstripped supply, and deliveries have been delayed. It's a good thing, too.

Sales of iPads fell 18% in the quarter, according to ComputerWorld. The decline was worse than expected, in part because consumers were waiting for the new device to be launched. Whether the frenzy will last remains to be seen.

While reviews of the device have been largely positive, they haven't been as fawning as they have been for other Apple products. For instance, Eric Limer at Gizmodo argued that the Nexus 7 offers consumers a better value. Others, such as Jessica Dolcourt at CNET, say the Mini's deficiencies are glaring.
 
"Certainly existing Apple fans will gravitate toward it, but there's a question mark over how good the Mini actually is," she wrote. "It's lighter and thinner than the competition, but the screen resolution lacks Apple's crystal clarity, and the battery life is on par with rivals, but won't surpass it."

Of course, the iPad Mini has got plenty going for it. The device's size and price point may make it attractive for the education market. Apple will sell plenty of Minis during the holiday season. The company also plans to launch an online radio service to compete against Pandora (P), which will help bolster sales.

Apple, which sold 14 million tablets last quarter, controls about 70% of the tablet market, a level of dominance that clearly won't last, because it rarely does.

Besides the Nexus 7, Apple faces pressure from Microsoft (MSFT)'s new Surface tablet, though reviews have been harsh. Amazon.com (AMZN) may be the most formidable rival. The e-commerce behemoth, which on Thursday reported a $274 million loss, sells its Kindle e-readers at cost. Uneconomical competitors are always the toughest. (Microsoft owns and publishes Top Stocks, an MSN Money site.)

Apple's best days are not behind it, but its days ahead will certainly be challenging.

Jonathan Berr does not own shares of the listed shares. Follow him on Twitter@jdberr@gmail​.com