No piece of software is perfect. Many users were facing Wi-Fi issues when they updated to iOS 6.0.0 and to stop that Apple released iOS 6.0.1 but many users still faced the issue. To try to solve this, Apple has now released iOS 6.0.2 which is only for iPhone 5 and iPad Mini. If you were facing the issue, you should download and install this on your device.
Download links for this and various IPSW's can be found by clicking here.