My iPhone 5 WiFi speeds with iOS 6.0.2 are the same as with 6.0.1 and not a problem.
You might try Settings -> General -> Reset -> Reset network settings to see if that helps.
Note also that you aren't addressing Apple here. This is a user to user technical help forum hosted by Apple.
To send feedback to Apple use http://www.apple.com/feedback/iphone.html
Note also that Speedtest results are highly variable depending on network traffic, etc.