Many Apple analysts today, though, remain confident that Apple will be able to maintain its strong position in the high end of the smartphone market. They noted that the updates were more evolutionary than revolutionary.
Piper Jaffray analyst Gene Munster called the Galaxy S4 "an incremental update akin to iPhone S models." The updates largely were evolutionary, he noted, and while some of the software features are "unique," the improvements are "minor compared with what Siri was to the iPhone 4S or even Google Now to Android."
As a result, he expects Apple to maintain a low 40 percent share of the high-end market. JK Shin, head of Samsung's mobile business and the company's newly appointed co-CEO, told The Wall Street Journal that he's not satisfied with Samsung's market share in the U.S.
And Jefferies analyst Peter Misek said that while he was impressed overall with the device, he's waiting "to see how the features perform in the real world and if they are actually used." He added that a major complaint among Galaxy users is they don't like Samsung's customized software.
"We believe the S4 will certainly sell well and it is incrementally negative for Apple," Misek said. "However, the device is not revolutionary, in our view. Aside from the large screen size, which we believe gives Samsung a large advantage over Apple, we believe many of the features can easily be replicated."
Sterne Agee analyst Shaw Wu, meanwhile, said Apple supplier checks indicate Apple is cutting iPhone production plans as it prepares for a device refresh in the second half of the year. He also believes Apple is sourcing components for the iPhone 5S and a lower-cost iPhone.
However, Wu doesn't expect Apple to release an iPhone with a bigger screen until 2014.
"We continue to believe AAPL is leaving money on the table by not participating in larger touchscreen form factors dominated by Android vendors," he noted. "But more importantly, we believe AAPL needs to reclaim high-end leadership as that is what its brand is about."
Apple shares grew 1.6 percent to $439.42 in early trading today. Samsung shares trading in Korea closed down 2.6 percent.