Although Apple quickly fixed their delete test page that caused problems with user's wifi connections on their new iPhone 5s, that is not the real issue.

There is still a huge issue with iOS 6 and possibly iPhone 5 hardware. The forums are buzzing with users having issues and returning phones. Apple is currently silent on the issue.

A few threads:
Anyone still having IOS 6 wifi issues?
iOS 6 WiFi Disabled
iPhone 5 wifi issues
iPhone 5 wifi signal strength issues

I have the same problems. iOS 6 causes iPad 2 wifi issues. The signal has a very short range, the speeds are slow, and the connection constantly drops.

The iPhone 5 wifi is way to weak and also constantly drops.

iOS 6 on 3GS iPhone the wifi works fine. The signal has a long range, the speeds are very fast, and the connection does not drop at all.

iOS 6 and iPhone 5 have zero range. I have 2 PC laptops, 1 MacBook, and 2 3GS phones that are fine in our living room. iPhone 5's and iPad 2 lose their connections. If I stand right next to the router, the iPhone 5s and the iPad 2 work fine. If I walk 10-15 feet away I lose the connection. My other equipment works in the back yard which is 50 -75 ft away and through several walls.

At 15 feet away my 3GS has 10 times the speed of my iPhone 5. Several videos have been posted showing the issue. Here is one.

THIS IS NOT GOOD!!!