Apple co-founder Steve Wozniak famously said the iPhone X would be the first model of the device he would not get on day one. In December, Apple CEO Tim Cook sent "The Woz" — as he is often called — an iPhone X.

And the Woz's verdict? "Plus and minus," he told CNBC in an interview on Monday.

When he got the device he criticized the Face ID function, which lets you unlock the phone with your face, saying that he prefers using a fingerprint.

And he also had an issue with the home button that is located on the side of the device. It has a number of functions, such as activating Apple's voice assistant Siri or to wake the handset up. A few months on, The Woz is still not impressed by the home button.

"The greatest thing about the iPhone X for me is a little more screen space that's in my pocket. As far as the face ID, it really hasn't worked as well for me as Touch ID and I really like the ones where you touch on the back. It hasn't been like, 'Oh my gosh, it's the greatest thing in the world,'" Wozniak said.

"The worst thing about it is the combination power and home key button which has about eight different functions in terms of when you push it and how you push it and how long you push it. It's kind of confusing... and that's not the nature of Apple products."

Wozniak, who co-founded Apple with Steve Jobs in 1976, spoke to CNBC at an event at the Money 20/20 conference in Amsterdam, Netherlands, hosted by Feedzai.

Apple's annual developers conference also kicks off Monday. Several rumors have suggested that the company could unveil a refreshed version of its lower-priced iPhone SE. This could help it continue to grow iPhone sales with people who don't want to fork out for the $999 iPhone X, but also in emerging markets such as India.

"I'm actually for the lower cost models," Wozniak said. "At one point, we actually introduced two iPhones — the iPhone 5C and the iPhone 5S. The S had the fingerprint detection, the C did not. It was $100 cheaper, a smaller, little classic-y looking phone.

"I loved that phone. I loved the design of it. I think it was one of the best designs Apple ever did for how it looked and felt and did the main things for a good price. It was a good trade-off. So I think that is an appropriate place for Apple to be."