Despite decent initial reviews, both the G1 phone and the Android operating system powering it have some significant flaws, according to an expert.

Android restarts itself often, resulting in the constant resetting of the device clock and other key measures, according to a review written by Nomura analyst Richard Windsor.

It is impossible to sync personal data to the phone without going through Google, according to the review, which makes the process unwieldy.

This comes as Android has already been panned by Sprint CEO Dan Hesse as not yet “good enough to put the Sprint brand on it.” 

In a slowing economy in which the G1 is competing with heavily marketed rivals from Apple, Nokia, and RIM, Android’s flaws and Mr. Hesse’s negative review could dampen demand for the G1.

Android is in its infancy, meaning the software will likeley be changed without warning. In this open-standards environment, it could force developers to suddenly rewrite applications. There will be no guarantee of backward compatibility.

“This is a simple issue of maturity,” Mr. Windsor said in his review. “The current version is 1.0, meaning that it is Google’s first attempt at putting mobile phone software into the wild.”

Mobile operating systems have a tough task. They act as the connection between mobile devices’ hardware and applications. But they operate in a restricted environment in which bandwidth, processor power, battery power, and network connectivity are ever important. The switch to 3G wireless broadband has made the task of any new operating system yet more difficult.

Mr. Windsor also saw at least one pesky hardware problem. The plastic hinge on which the screen swivels to reveal the keypad is “a warranty disaster waiting to happen,” he wrote

“We think that no handset maker would have included such a potential liability, and therefore we believe that this was a requirement imposed by Google,” he said.

But Mr. Windsor, who overall approves of the G1, has been wrong about the HTC-made handset before. He recently forecast the sale of 100,000 devices in the fourth quarter. He has upgraded that to 500,000, well short of the G1’s 1.5 million preorders.

“We think the device will sell reasonably well as it performs much better than we would have expected,” he wrote.