James Martin/CNET

Apple's iPhone 4S has earned high marks from owners, a new study from ChangeWave Research has found.

According to the research firm, which conducted a survey of 215 iPhone 4S owners last month, 77 percent of them are "very satisfied" with Apple's handset. Another 19 percent of owners say that they are "somewhat satisfied" with the device. Just 2 percent of respondents told ChangeWave that they are "unsatisfied" with the iPhone 4S.

The 96 percent satisfaction for the iPhone 4S trumps the level for the iPhone 4, which earned accolades from 93 percent of respondents last year. In that study, 72 percent of iPhone 4 owners said that they were "very satisfied," while 21 percent claimed they were "somewhat satisfied."

The iPhone 4S is also a favorite of smartphone reviewers. When it launched in October, CNET's Kent German gave the iPhone 4S four stars out of a possible five, saying that the device is a fine option for any consumer looking for a smartphone.

ChangeWave Research

"The iPhone 4S isn't the king of cell phones, but it's part of the royal family nonetheless," German wrote. "Even without 4G and a giant screen, this phone's smart(ass) voice assistant, Siri, the benefits of iOS 5, and its spectacular camera make it a top choice for anyone ready to upgrade."

Speaking of Siri, ChangeWave found that the voice assistant is the feature nearly half of iPhone 4S owners like most about the handset. The device's ease of use, 8-megapixel camera, and faster Web browsing also earned high marks.

But it wasn't all good news for Apple. The iPhone 4S' persistent battery life issue was cited by 38 percent of respondents as the feature they "dislike most" about the smartphone. Apple's resistance to 4G connectivity was an issue for 30 percent of owners, while 11 percent of respondents said that they wish the iPhone 4S screen was bigger.

Although owners also complained of excessive dropped calls, it appears the iPhone 4S is doing a much better job than its predecessor. ChangeWave found that 2.5 percent of iPhone 4S owners have been frequently dropping calls, compared to 5.2 percent of iPhone 4 owners.

Further digging into iPhone 4S drop rates reveals that it's largely an AT&T issue. In fact, ChangeWave said that just 1.3 percent of Verizon iPhone 4S customers experience frequent drops, while 4.1 percent of AT&T customers see high dropped-call rates.