In a series of tweets this week, a former Apple engineer named Bob Burrough, who recently founded a 3D printing company named Bilt It, said that Cook has dramatically changed Apple in ways that he believes stifles innovation and fundamentally alter the corporate culture late Apple co-founder Steve Jobs created.

“The very first thing Tim did as CEO was convert Apple from a dynamic change-maker into a boring operations company,” Burrough said in a tweet this week. He added in a subsequent tweet that the company’s corporate culture is “vastly different today than it was five years ago.”

Cook was appointed Apple’s (AAPL) CEO in 2011, succeeding Jobs, who stepped down during his battle with cancer. Over the years, Cook has put his mark on Apple’s culture, focusing it more on charitable donations than it had in the past. Cook has also doubled down on environmental initiatives.

Get Data Sheet, Fortune’s technology newsletter

Cook has tried to maintain secrecy—an Apple hallmark when Jobs was leading the company—but leaks continue to surface to the chagrin of Cook and his team. The Apple chief executive’s reign has also been characterized as one without a major new product on the scale of the iPhone or another similarly popular device.

However, Cook has also grown Apple’s revenues and profits to mew heights and the company’s cash coffers are busting at the seams. By nearly all measure, Apple is financially healthier now than ever.

But Apple has also lost some of the allure it once enjoyed under Jobs, and some have blamed Cook for that. Even Apple’s top executives have acknowledged that Cook is a much different person than Jobs.

“Steve was in your face, screaming, and Tim is more quiet, more cerebral in his approach,”Apple’s senior vice president of Internet software and services Eddy Cue told Fast Company in an interview in August. “When you disappoint Tim, even though he isn’t screaming at you, you get the same feeling. I never wanted to disappoint Steve, and I never want to disappoint Tim. [Other than them,] I have that feeling with, like, my dad.”

For more about iPhone, watch:

Burrough in his tweets and in an interview with CNBC that those differences have fundamentally changed Apple. He went so far as to tell CNBC that Apple is now operating like Palm, another company he worked for that eventually folded its smartphone business after the iPhone proved too difficult to compete with.

“Working at Palm, the teams were highly organizational, [hierarchical] and responsibilities were siloed,” Burrough said. “There was a clear sense that each person had a clear responsibility, and rarely deviated from it. When you went to someone for help solving a problem ‘not my job’ was a common response.”

But in his interview with Fast Company last year, Cue rebuffed claims that Cook’s Apple isn’t innovative. In fact, he said that innovation is as alive under his current boss as it was under the iconic Steve Jobs—something Burrough doesn’t see.

“The world thinks we delivered [a breakthrough] every year while Steve was here,” Cue said. “Those products were developed over a long period of time.”