iPhone 5 users reporting WiFi issues
According to forums for Apple and MacRumors, many iPhone 5 owners are complaining of Wifi slowness or no connectivity at all. Mentioned by MacRumors, this may be an issue specifically with WPA2 encryption, as some users are reporting success with switching to the less-secure WEP. Some report issues with one iPhone 5, but another on the same network has no issues at all.
I haven't tried switching my Airport Extreme Base Station N to WEP yet, but I have had issues myself with simple YouTube video streaming, both in Safari and in the YouTube app itself. Occasionally it will work, but slowly. LTE however, works flawlessly. A couple of Speedtest.net app runs, also show inconsistant results when connected via WiFi.
Are you experiencing issues? Post up in the comments.