Still, the price premium for tablet PCs is a real problem for further adoption and not helped by the fact that conventional laptop prices have come down in recent years, Shim said. When first introduced, tablet PCs cost as much as $800 more than a laptop, compared with $200 to $300 today, which shows there has been some improvement, he noted.

2. Touch technology hasn't caught on.

Despite the advantages of handwriting and touch to some vertical market users, touch technologies with a finger or a special electronic pen used in tablet PCs have not caught on in the mainstream.

The main reason they haven't caught on is that the keyboard is already widely used and is growing more acceptable to use every day, said Ken Dulaney, another Gartner analyst. "Many people have learned to type out of school," he said. Text messaging and instant messaging only contribute to the willingness to use keys for input, several analysts said.

Also, touch technologies in early tablet PCs have not been that accurate, unless the application is forms-based with boxes to check, Shim said. Touch also has not been promoted by vendors.