Researchers at Nielsen Norman Group concluded that the average success rate in completing tasks on a mobile browser is 59%. The rate jumps to 80% on a PC and a whopping 75% on the iPhone.
The researchers had a number of individuals perform tasks such as look up movie listings and shop for earrings using their own mobile device. They also gave the participants open ended research questions. Success was measured by the amount of time it look to perform a task.
The study found that people still get things done much faster on a PC. When a test subject used a website designed for mobile phones, their success rate and time jumped.
The study teaches us absolutely nothing new.