Sales of the mobile device are closely watched on Wall Street, seen as a bellwether for the performance of the world's most valuable company. Shares of Apple were down 1 percent on Friday, but were still on track for their best week since 2011.
IPhone sales also important part of the holiday season for retailers: Before the launch of the iPhone 7, retailer Target posted a double-digit same-store sales decline in electronics during the second quarter, including a "significant drag" due to a 20 percent slide in sales of Apple products.
Industry watchers have given the new handset reviews that are solid, but not earth-shattering. Still, Bernstein analyst Toni Sacconaghi said that the pool of existing iPhone users is about 50 percent higher than two years ago, which could raise iPhone sales to consumers in need of an upgrade, regardless of the 7's specs.
"Really with the Samsung recall, the carriers have one new premium-tier phone, and they've been very aggressive with the subsidies. It's really surprised us," Mike Walkley, Canaccord Genuity analyst, told CNBC's "Squawk on the Street" on Friday. "So basically, as a U.S. consumer, if you've paid off your iPhone 6 through your installment plans, you'r basically going to get the iPhone 7 for free."