Upgraded iPhone 4S to iOS6. Experiencing WiFi intermittent connection

I have an iPhone 4S, working perfectly with iOS5.

I loaded iOS6 on Saturday (9/29) and immediatly experienced the intermittent issues with WiFi at different locations (Home, shops, etc - meaning not being my home network). This still fails even after doing a full back to factory RESTORE by now 3 times, w/o any loaded apps running, the simple try to activate the phone shows the problem.

Is this a Firmware compatibility issue with respect to the iOS6? Or truly just a iOS6 issue?

Are there different iPhone 4S firmware levels?

In my opinion, Apple should allow us to go back to iOS5 while we wait for resolution, if there is ever one.