Wozniak criticised the iPhone's lack of 3G connectivity, pointing out that 3G is essential for an internet device.
He has previously criticised the decision to cut the price of the phone by $200 shortly after launch.
"I was really disappointed when the iPhone was introduced," Wozniak said during a press conference following his keynote speech at the Broadband and Beyond Conference in Sydney today.
"Half the phones in the AT&T store at the time were 3G phones. I was shocked because Apple is bringing the full internet [to mobiles] - full web pages with pictures and everything - and it's not 3G and I knew that would be a speed detriment."
Wozniak added that, while he still uses an iPhone, he prefers a Motorola Razr for calls and internet access.
The Apple co-founder also criticised the MacBook Air, which he felt had made too many hardware tradeoffs to achieve a thin form factor.
"I don't think it's going to be a hit. I'm trying to figure out a way to make the Air a part of my life because I'm a one-laptop-only person," he said.
"I don't feel it's a benefit if you have to carry the Air plus a DVD player plus a couple of extra dongles to connect to Ethernet things and also maybe an extra hard disk to carry your music."
Wozniak has gained something of a reputation for openly criticising Apple if he feels the company is making a mistake.
He was unhappy when the firm moved to Intel processors, for example, but said that Apple chief executive Steve Jobs "very seldom" calls him up to complain about his stance.
"We're really good friends - never argued over these things - but once in a while he will just have a comment, 'thanks a lot'."
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