By Slash Lane

Published: 12:30 PM EST (09:30 AM PST)

The NPD Group revealed this week that customers who bought an iPad at launch are extremely satisfied with the device and use it quite often, but more recent purchasers are less active with their tablet.

Stephen Baker, vice president of industry analysis with NPD, revealed on the company's official blog that customer satisfaction with the iPad is very strong, but early adopters are more satisfied. The survey, conducted in August, found that 65 percent of customers who bought the iPad after launch said they are "very satisfied" with their purchase.

That's a decrease from the nearly 80 percent who said they were "very satisfied" with their purchase at launch. NPD separated the two groups by considering anyone who bought in the first two months of availability as an "early adopter."

The survey also found that early iPad adopters use the device for more than 18 hours per week, and for almost a third of users, that time is increasing.

"Clearly early adopters love their iPads and are finding increasing opportunities to use them," Baker wrote.

The most popular tasks are surfing the Internet, handling e-mail and playing games. Early adopters are also 44 percent more likely than more recent buyers to watch YouTube videos, 50 percent more likely to watch movies, 60 percent more likely to watch TV shows, and 38 percent more likely to read e-books.

As for complaints about the iPad, 51 percent said they were most dissatisfied about the lack of USB ports. Following that were lack of printing and multi-tasking, both of which will be resolved with the release of iOS 4.2 in November.

In addition, NPD said on Friday that it found 87 percent of iPad sales have been purchases in addition to a traditional computer, suggesting Apple's tablet is not "cannibalizing" the PC market.

The study found that an overwhelming majority of users purchased an iPad as an "incremental" device, rather than one intended to replace an existing computer. In fact, 24 percent said they planned to purchase an e-reader in addition to an iPad.

"Early adopters, like iPad owners, follow a traditional pattern of consumer behavior; they purchase products because they want them, not because they need them," Baker said. "However, as Apple increases iPad distribution and consumer interest peaks, the profile of an iPad owner is much more likely to mirror the overall tech population. When that does happen other tech products with similar usage profiles as the iPad, such as notebooks, netbooks, and e-readers will come under increased pressure from the iPad."

"Until then, however, most iPad sales are likely to be incremental additional technology devices in the home, rather than a one-for-one replacement of a planned purchase."