With this week marking the 10th anniversary of the unveiling of Apple's  (AAPL) first-ever iPhone, now seems like a good time to compare the tenures of Steve Jobs with his replacement as CEO over the last five-and-a-half years, Tim Cook.

When Jobs officially regained control in 1997 over the company he helped found, Apple shares sat near the equivalent of $0.79 apiece, accounting for two separate two-for-one stock splits during his tenure, and a later seven-for-one split. By the time he resigned as CEO in 2011, shares had skyrocketed more than 6,000% to the equivalent of about $54 per share. Over Jobs' tenure, therefore, the compound annualized rate of return was about 35%.

In Cook's time so far as CEO, the stock has more than doubled to around $119, for a compounded annualized rate of return of roughly 16%.

For his part, Cook has put a far greater focus on bringing money back to shareholders than Jobs did as Apple's explosive growth as a smaller company has slowed. Since July 2012, Apple has issued a regular quarterly dividend of as much as $3.29 per share, and the company has also repurchased more than $127 billion in shares under Cook. When Jobs was CEO, Apple only issued a dividend twice. 

And to his credit, Cook has excelled in creating and growing Apple's services segment through the App Store, Apple Music, Apple Pay and iCloud. In early 2016, the services segment surpassed revenue for the Mac segment for the first time and became Apple's second-most profitable unit, behind the iPhone. In fiscal 2016 it earned the company about $24.3 billion, or roughly 11% of total revenues.

But despite his successes, Cook faces a challenging environment in the upcoming years as smartphone sales cool. For 2016, IDC recently predicted that worldwide mobile phone shipments will reach a total of 1.93 billion units, down 2.1% from the 1.98 billion units shipped in 2015. By 2020 total mobile phone shipments are expected to be essentially flat at 1.98 billion units worldwide.

Apple is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells AAPL? Learn more now.

Cook noted to the Post recently that he is not the traditional CEO in that he doesn't consume himself with "the profit and loss... the revenue statement, the income and expense, the balance sheet."

"Those are important, but I don't think they're all that's important," Cook said. "There's an incredible responsibility to the employees of the company, to the communities and the countries that the company operates in, to people who assemble its products, to developers, to the whole ecosystem of the company."

The 56-year-old executive recently took a 15% pay cut for the 2016 fiscal year because Apple failed to meet its revenue and profit goals for the year.

But University of Maryland business professor Peter Morici said on Fox Business' "Varney & Company" on Jan. 6 that the cut isn't outrageous. "He's doing a pretty good job in a pretty tough environment," Morici said.

Cook has also made good on his vision to remain responsible to the communities and the people that Apple affects.

Under Cook the company has increased its efforts to invest in sustainability, working with the Conservation Fund to conserve over 36,000 acres of forest in the U.S. in 2015. And the company's new campus, slated to open later this year, will run entirely on clean energy. Cook himself has acted as an advocate for LGBTQ youth after coming out as the first openly-gay CEO of a major U.S. corporation in 2014, a decision which he told the Post was motivated by helping children.

Still, the company has faced criticisms recently for slowing down innovation in its devices and for failing to introduce any truly groundbreaking products. One of Apple's newest products, the Apple Watch, has seen mixed results and in the 2016 third quarter saw a 72% year-over-year decline in shipments. "It has become evident that at present smartwatches are not for everyone," Jitesh Ubrani, analyst at IDC, said in a recent report. "Moving forward, differentiating the experience of a smartwatch from the smartphone will be key."

And even some of Apple's long-standing product lines have begun to languish. Apple's computers have long been neglected,with the iMac and Mac Pro desktops remaining untouched and un-updated for years as MacBook Pro was given an underwhelming update this year.

Meanwhile, 10 years and seven generations after the iPhone was first released, the company is still attempting to evolve the product nearly every year. The iPhone 7 and 7 Plus, unveiled in September 2016, haven't quite lived up to that promise, however. Analysts have said that demand for the device is slightly higher than the 6S version, but has not wowed. The company is also reportedly cutting iPhone 7 production by 10% for the first quarter of 2017.

But that could change later this year as Apple rolls out the 10th-anniversary iPhone 8. The newest model is rumored to include a larger OLED screen, wireless charging, facial and retinal scanning and augmented reality capabilities.

Perhaps the best comment about the job Cook has done relative to Jobs comes from Cook himself.

"To me, Steve's not replaceable -- by anyone," Cook told The Washington Post in an August 2016 interview. "He was an original of a species. I never viewed that as my role."

More from Stocks

Dow Futures Pop Despite Rising Trade War Fears

Dow Futures Pop Despite Rising Trade War Fears

Why GE's Stock Has Fallen 9% in the Last 30 Days

Why GE's Stock Has Fallen 9% in the Last 30 Days

5 Stock Picks Under $10 for Millennials

5 Stock Picks Under $10 for Millennials

3 Complicated Investing Strategies Millennials Love

3 Complicated Investing Strategies Millennials Love

Tyson Foods CEO: We Aren't Done Making Deals

Tyson Foods CEO: We Aren't Done Making Deals