I've had no problems detecting and connecting to wifi at my school, work, or home using 6.0.1 on my iPad 2, but ever since the new 6.1 update, my iPad fails to recognize any wifi connection points, and drops signal numerous times. I've troubleshooted by restoring numerous times, and updating router firmware to see whether it was a internet problem. Nothing worked so I am leaning towards the idea that the 6.1 update had something to do with this, or my wifi antenna just decided to screw up out of the blue.
In the photo link below, I have a 4th gen iPod touch running 6.1 sitting on top of my iPad 2 connected to the wifi router at my 1 bedroom apartment. This picture was taken about 10 feet away from the router. My access point is named cr1z_sys.
As you can see, the iPad and iPod are both connected to the same connection, but the iPad has a weaker signal, and has failed to detect other access points. The other access points don't matter as this is my home, but my point here is to show if you were in a public area, you wouldn't be able to detect a access point that was a bit further away.
I have an appointment today at the Genius Bar to see if this is a hardware issue, although I doubt it.