iPhone 4 has one significant issue: reception. Vista has countless issues...
Please, Microsoft. Don't put yourself in a same sentence as Apple. It's like a Yugo being compared to a Bentley.
iPhone 4 actually has two significant issues. One is reception and the other is the proximity sensor. Apple has been quite vocal on how to somewhat get around the reception issue (buy a case/bumper), but they have been strangely silent on the issue with the proximity sensor.